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Full text of "Byte Magazine Volume 06 Number 12 - Computer Games"

DECIMS^R mi Vol. 6, Ho. 12 
libation 




MPUf ER GAMES 



INSERT 25 SECTOR DISK 



A new small computer 
that won't limit you tomorrow 




New Cromemco System One shown with our 
high-capability terminal and printer. 



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Expandability 



Here's a low-priced computer that won't run out 
of memory capacity or expandability halfway 
through your project. 

Typically, computer usage tends to grow, requir- 
ing more capability, more memory, more storage. 
Without a lot of capability and expandability, your 
computer can be obsolete from the start. 

The new System One is a real building-block 
machine. It has capability and expandability by the 
carload. 

Look at these features: 

■ Z80-A processor 

■ 64K of RAM 

■ 780K of disk storage 

■ CRT and printer interfaces 

■ Eight S-100 card slots, allowing expansion 
with 

— color graphics 

— additional memory 

— additional interfaces for telecommunica- 
tions, data acquisition, etc. 

■ Small size 

GENEROUS DISK STORAGE 

The 780K of disk storage in the System One 
Model CS-1 is much greater than what is typically 
available in small computers. But here, too, you 
have a choice since a second version, Model 
CS-1H, has a 5" Winchester drive that gives you 
5 megabytes of disk storage. 

MULTI-USER, MULTI-TASKING 
CAPABILITY 

Believe it or not, this new computer even offers 
multi-user capability when used with our advanced 
cromix* operating system option. Not only does this 
outstanding O/S support multiple users on this com- 
puter but does so with powerful features like multi- 



ple directories, file protection and record level lock. 
cromix lets you run multiple jobs as well. 

In addition to our highly-acclaimed CROMIX, there 
is our cdos*. This is an enhanced CP/M + type system 
designed for single-user applications, cp/m and a 
wealth of CP/M-compatible software are also 
available for the new System One through third- 
party vendors. 

COLOR GRAPHICS/WORD PROCESSING 

This small computer even gives you the option of 
outstanding high-resolution color graphics with our 
Model SDI interface and two-port RAM cards. 

Then there's our tremendously wide range of 
Cromemco software including packages for word 
processing, business, and much more, all usable 
with the new System One. 

ANTI-OBSOLESCENCE/LOW-PRICED 

As you can see, the new One offers you a lot of 
performance. It's obviously designed with anti- 
obsolescence in mind. 

What's more, it's priced at only $3,995. That's 
considerably less than many machines with much 
less capability. And it's not that much more than 
many machines that have little or nothing in the 
way of expandability. 

Physically, the One is small — 7" high. And it's all- 
metal in construction. It's only 14Ya" wide, ideal for 
desk top use. A rack mount option is also available. 

CONTACT YOUR REP NOW 

Get all the details on this important building-block 
computer. Get in touch with your Cromemco rep 
now. He'll show you how the new System One can 
grow with your task. 



"CROMIX and CDOS are trademarks of Cromemco Inc. 
tCP/M is a trademark of Digital Research 



kTM 



a Cromemco 
Incorporated 
280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040 • (415) 964-7400 
Tomorrow's computers today 



Circle 111 on Inquiry card. 





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CROMIX FILE SYSTEM 

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CROMIX* — Cromemco's outstanding 
UNIX — like operating system 



cromix is just the kind of major 
development you've come to expect 
from Cromemco. After all, we're 
already well-known for the most 
respected software in the microcom- 
puter field. 

And now we've come up with the in- 
dustry's first UNix-lookalike for 
microcomputers. It's a tried and proven 
operating system. It's available on both 
5" and 8" diskettes for Cromemco 
systems with 128K or more of memory. 

Here are just some of the features you 
get in this powerful Cromemco system: 

• Multi-user and multi-tasking 
capability 

• Hierarchical directories 

• Completely compatible file, 
device, and interprocess I/O 

• Extensive subsystem support 

FILE SYSTEM 

One of the important features of our 
cromix is its file system comprised of 
hierarchical directories. It's a tree struc- 
ture of three types of files: data files, 



*CROMtX is a trademark of Cromemco, Inc. 
tUNIX is a trademark of Bell Telephone Laboratories 



directories, and device files. File, 
device, and interprocess I/O are com- 
patible among these file types (input and 
output may be redirected inter- 
changeably from and to any source or 
destination). 

The tree structure allows different 
directories to be maintained for different 
users or functions with no chance of 
conflict. 

PROTECTED FILES 

Because of the hierarchical structure 
of the file system, cromix maintains 
separate ownership of every file and 
directory. All files can thus be protected 
from access by other users of the 
system. In fact, each file is protected by 
four separate access privileges in each 
of the three user categories. 

TREMENDOUS ADDRESS SPACE, 
FAST ACCESS 

The flexible file system and general- 
ized disk structure of cromix give a disk 
address space in excess of one gigabyte 
per volume — file size is limited only by 
available disk capacity. 



Speed of access to disk files has also 
been optimized. Average access speeds 
far surpass any yet implemented on 
microcomputers^ 

'C COMPILER AVAILABLE, TOO 

Cromemco offers a wide range of 
languages that operate under cromix. 
These include a high-level command 
process language and extensive sub- 
system support such as cobol, Fortran 
iv, ratfor, lisp, and 32K and 16K basics. 

There is even our highly-acclaimed 
'C compiler which allows a program- 
mer fingertip access to cromix system 
calls. 

THE STANDARD O-S 
FOR THE FUTURE 

The power and breadth of its features 
make cromix the standard for the next 
generation of microcomputer operating 
systems. 

And yet it is available for a surprisingly 
low $595. 

The thing to do is to get all this 
capability working for you now. Get in 
touch with your Cromemco rep today. 



m 



Circle 112 on inquiry card. 



Cromemco 



^^^M 280 BERNARDO AVE., MOUNTAIN VIEW, CA 94040 

^^^^ Tomorrow's computers today 



(415)964-7400 



Volume 6, Number 1 2 




In The 



Features 

30 The Colnless Arcade by Gregg Williams / With 
microcomputer games, you can have your fun and your quarters 
too. 

42 Build a Touch Tone Decoder for Remote 
Control by Steve Ciarcia / Once you get your computer to 
answer the telephone and decode tone signals, you can use it for 
remote control. 

134 Color Computer from A to D, Make Your 
Color Computer "See" and "Feel" Better by William 

Barden Jr / Hardware and software projects to tie your Color 
Computer to the real world. 

1 66 The Atari Tutorial, Part 4: Display-List 

Interrupts by Chris Crawford / How to get the most out of 
the Atari 400 and 800's color-graphics features. 

I 90 How to Build a Maze by David 

Matuszek / Generate unique random mazes for puzzles and 
games. 

1 98 Toward a Structured 6809 Assembly 
Language, Part 2: Implementing a Structured 
Assembler by Gregory Walker / Implementing GOTO-iess 
structure in an already existing language is easy with 
macroinstructions. 

229 MIKBUG and the TRS-80, Part I : A Cross- 
Assembler for the Motorola 6800 by Robert 

Labenski / A TRS-80 cross-assembler package for those who are 
tired of hand-assembling code and loading it two bytes at a time 
into MIKBUG. 



M66 



452 



Online Information Retrieval: Promise and 
Problems by Steven K Roberts / The public must be 
convinced that online databases provide efficiency, economy, and 
convenience. 

474 Handl-Wrlter, A Video Note Pad for the 

Physically Handicapped by Howard Batie / How to turn 
the TRS-80 into a communications device for severely 
handicapped persons. 



Reviews 

24 Robotwar by Curtis Feigel 

74 BYTE's Arcade: Olympic Decathlon by David A Kater; 
Missile Defense vs ABM by Robert Moskowitz; Gorgon by Peter 
V Callamaras; Commbat: A Tele-Game for Two by George 
Stewart 

I 08 alphaSyntauri Music Synthesizer by Steve Levine and Bill 
Mauchly 

1 63 Battle of the Asteroids by Gregg Williams 
304 Pascal-80 by Rowland Archer 
486 Starfighter by Eric Grammer 



Nucleus 



258 



What Makes Computer Games Fun? by 

Thomas W Malone / Why the average outer-space game may 
be more educational than many classroom drill-and-practice 
programs. 



320 



Computer Scrabble by Joseph J Roehrig / Give 
your computer a vocabulary and challenge it to a fascinating 
game of micro-Scrabble. 



Generating Programs Automatically by 

Jacob R Jacobs / Three utility programs help write the Applesoft 
BASIC program for you. 



366 



BYTE's Cumulative Index prepared by 
Microcomputer Information Services / Our six-year 
cumulative index will put an end to your random searches 
through past issues of BYTE for that specific article. 



6 Editorial: New Games, New Directions 

1 4 Letters 

22, 1 32 BYTE's Bits 
1 32, 483 Book Reviews: AIM 65 Laboratory Manual and Study 

Guide: Apple Machine Language 
252 Ask BYTE 

278 System Notes: The Game of Left/Right 
302 BYTE Game Contest 
314 BYTELINES 
462 Event Queue 

465 Books Received 

466 Clubs and Newsletters 

467 Software Received 

469 Technical Forum: Apple XIO Control 
484 Languages Forum: APL Runs Circles 
489 What's New? 

542 Unclassified Ads 

543 Reader Service 

544 BOMB, BOMB Results 



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Page 190 



December 1981 © BYTE Publications Inc 3 



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Editor in Chief 
Christopher Morgan 

Manaalna Editor 

Mark Haas 

Technical Editors 

Gregg Williams, Senior Editor; 
Richard S Shuford; Curtis P Feigel; 
George Stewart; Arthur Little; 
Stanley Wszola; Charles Freiberg, 
New Products Editor; Steve Garcia; 
Mark Dahmke; Philip Lemmons, 
Consulting Editors; Jon Swanson, 
Draftsman 

Copy Editors 

Beverly Cronin, Chief; Faith Hanson; 
Warren Williamson; Anthony J Lockwood; 
Ann Graves; David R Anderson; 
Bob Reinert; Linda M Evers 

Assistants 

Faith Ferry; Debe Wheeler; 
Karen A Cilley; Susan Ferber; 
Marie Hennessy 



Production 

Nancy Estle, Director; Christine Destrempes, 
Asst Director; Jonathan M Graves, Creative 
Consultant; Wai Chiu Li; Patrice Scribner; 
Damian Henriques; Jan Mullen 
Linda J Sweeney; Sherry McCarthy, 
Chief Typographer; Debi Fredericks; 
Donna Sweeney; Valerie Horn 

Advertising 

Thomas Harvey, Director; Marion Carlson; 
Rob Hannings; Marilyn Williams; 
Deborah Porter; Vicki Reynolds; 
Cathy A R Drew; Jacqueline Earnshaw. 
Reader Service Coordinator 

Circulation 

Gregory Spitzfaden, Manager; 
Andrew Jackson, Asst Manager; 
Agnes E Perry; Barbara Varnum; 
Louise Menegus; Pinky Krulis; 
James Bingham, Dealer Sales; 
Deborah J Cadwell. Asst. 



Controller's Office 

Daniel Rodrigues, Controller; 

Mary E Fluhr, Acct. & D/P Mgr; Karen Burgess; 

Jeanne Cilley; Linda Fluhr; Vicki Bennett 

Traffic 

N Scott Gagnon; Michael Bacon; 
Scott Jackson 

Publishers 



Virginia Londoner; Gordon R Williamson; 
John E Hayes, Associate Publisher; 
Cheryl A Hurd; Michele P Verville, Publisher's 
Assistants; 



Officers of McGraw-Hill Publications Com- 
pany: Paul F McPherson, President; Executive 
Vice Presidents: James E Boddorf, Daniel A 
McMillan, III, Gene W Simpson; Senior Vice 
President-Editorial: Ralph R Schulz; Vice 
Presidents: Kemp Anderson, Business Systems 
Development; Robert B Doll, Circulation; James 
E Hackett, Controller; Eric B Herr. Planning and 
Development; H John Sweger. Jr., Marketing. 

Officers of the Corporation: Harold W 
McGraw Jr, Chairman and Chief Executive 
Officer; Joseph L Dionne, President and Chief 
Operating Officer; Robert F Landes, Senior Vice 
President and Secretary; Ralph J Webb, 
Treasurer. 




In This Issue 

Playing games may not be the most important task your computer does, but it sure 
makes for a lot of fun. As Robert Tinney's cover illustrates, computers play a central role 
in our recreational activites. BYTE's writers have been working hard at playing games, 
and their articles and reviews will help you pick and choose from among the many 
computer games available. Senior editor Gregg Williams speculates on the shape of 
games to come in the editorial, "New Games, New Directions." Thomas W Malone 
analyzes the attraction of computer games in "What Makes Computer Games Fun?" To 
learn how you can turn your game ideas into cash, see the rules for the BYTE Game 
Contest, page 302. 

On a more serious note, the Atari Tutorial continues with Part 4, "Display-List Inter- 
rupts" and William Barden Jr presents the first installment of a new series on Radio 
Shack computers, "Color Computer from A to D, Make your Color Computer 'See' and 
'Feel' Better." BYTE's six-year cumulative index will eliminate those random searches for 
that specific article. See page 366. All this, plus our regular features. 



BYTE is published monthly by BYTE Publications Inc, 70 Main St, Peterborough NH 03458. phone (603) 
924-928 1 , a wholly-owned subsidiary of McGraw-Hill, Inc. Address subscriptions, change of address, USPS Form 
3579, and fulfillment questions to BYTE Subscriptions. POB 590. Martinsville NJ 08836. Second class postage paid 
at Waseca, Minnesota 56093 - USPS Publication No. 528890 (ISSN 0360-5280). Canadian second class registra- 
tion number 932 1. Subscriptions are S 19 for one year, S 34 for two years, and S49 for three years in the USA and 
its possessions. In Canada and Mexico, S2I for one year, S38 for two years, S55 for three years. S43 for one year 
air delivery to Europe. S35 surface delivery elsewhere. Air delivery to selected areas at additional rates upon re- 
quest. Single copy price is S2.50 in the USA and its possessions, S2.95 in Canada and Mexico, S4.00 in Europe, 
and S4.50 elsewhere. Foreign subscriptions and sales should be remitted in United States funds drawn on a US 
bank. Printed in United States of America. 

Address all editorial correspondence to the editor at BYTE. POB 372, Hancock NH 03449. Unacceptable 
manuscripts will be returned if accompanied by sufficient first class postage. Not responsible for lost manuscripts or 
photos. Opinions expressed by the authors are not necessarily those of BYTE. Entire contents copyright © 1 98 1 
by BYTE Publications Inc. All rights reserved. Where necessary, permission is granted by the copyright owner for 
libraries and others registered with the Copyright Clearance Center (CCC| to photocopy any article herein for the 
base fee of S 1 .00 per copy of the article or item plus 25 cents per page. Payment should be sent directly to the 
CCC, 2 1 Congress St, Salem MA 1 970. Copying done for other than personal or internal reference use without 
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BYTE 8 is available in microform from University Microfilms International, 300 N Zeeb Rd, Dept PR, Ann 
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Subscription WATS Line: (800) 258-5485 

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Palo Alto CA 94303 


Costa Mesa CA 92626 



December 1981 © BYTE Publications Inc 



Circle 374 on inquiry card. 



MicroAn 

i an d t 
beyond 





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SCION Corporation pioneered advanced information display systems with the 

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computer. With MicroAngelo™ came a powerful, flexible CP/M* compatible, high 

level firmware called Screenware.™ For MicroAngelo™ Color System, Colorpak 

software evolved. Easy to integrate, easy to convert and easy to use. This software 

gave MicroAngelo™' unparalleled capacity to manipulate color transparencies. 

Beyond MicroAngelo.™ with the prototype Advanced Congressional Workstation 

developed for the U.S. Congress, SCION Corporation proved an interactive, very 

high resolution text/graphics display system can be built with existing technology. 

SCION Corporation grows at its unprecedented rate by evolving beyond today's 

triumphs, to develop graphics engines to solve tomorrow's problems. 

SCION Corporation. More than a graphics company. 

For information on the next generation of advanced information display systems, 

call today. If the image is important, it has to be SCION. 




If the image is important. 

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ACCESS/80 
ACCESS/80 
ACCESS/80 

The reason you bought 
your computer in the first 
place. 

Yoursystem is incomplete 
without the ability to ac- 
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Now you can have main- 
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Virtually any report you 
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and paper can be gener- 
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With user friendly AC- 
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ACCESS/80 is available in 
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Level I: Report Generator 
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Level II: Level I plus Out- 
put and Logic Pro- 
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Level III: Information man- 
agement System 
(Available 1st 
Qtr. 1982) -$795. 
Manual alone 
$65. 

ACCESS/80 requires CP/M™ or 
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supported include 8" IBM soft- 
sectored, NorthStar, Micropolis 
Mod. II, Superbrain 3.0, Apple II. 

SOFTWARE 
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ACCESS/80 trademark ol Enends Software CP/M 8 MP/M trademarks 
ol Digital Research RAMIS trademark Malrwnaio foe SPSS trademark 
SPSS Inc NOMAD trademark National CSS 



^ 



Editorial 



New Games 
New Directions 



by Gregg Williams, Senior Editor 



An editor leads a hard life, believe it or not. For example, in preparing for 
this issue, more than $1000 worth of game software passed across my desk 
before being returned to the manufacturers. This may sound like software 
heaven to you — it did to me at first. But even with this intriguing software 
temporarily floating around the office and my own computer and games to 
tempt me at home, I can't manage to spare an hour (let alone ten) playing the 
newest adventure game. 

Sometimes I'm not even sure I like games. But I know I like the idea — board 
games, card games, computer games, even books on game design. I think 
about games a lot and subscribe to two games magazines. Occasionally, I fan- 
tasize about designing the ultimate game, one that would leave the whole 
world breathless (and, not coincidentally, make me very wealthy). Looking 
for some family resemblance to games I enjoy, I search the face of every new 
game as if it were a person. The following sections depict a few of my findings. 

New Machines, New Games 

Games will take new directions with new machines. For sound and video 
graphics, the Atari 400 and 800 computers are hard to beat. These two 
machines have special hardware that accomplishes what most game program- 
mers have to do in software. This not only makes the game faster but also 
makes programming faster, simpler, and much easier. 

Another exciting machine is the IBM Personal Computer. Although I'll be 
reviewing it in-depth next month, several features are of interest to game 
players and programmers. First, the advanced disk BASIC has a number of 
very powerful commands for generating graphic images and music. You can 
store drawing and music commands as standard Microsoft BASIC string 
variables (somewhat akin to the "shape tables" for specifying graphic images 
in the Apple II). Not only can the program manipulate these strings, but a 
command string can refer to another string within its definition. The advanced 
BASIC also offers built-in commands for drawing and filling in rectangles, 
ellipses, circles, and pie wedges. Rectangular areas of graphics can be saved in 
arrays, then later returned to the screen with a single command. Light pens 
and joysticks are possible input devices, and advanced BASIC commands 
allow a BASIC subroutine to be executed when certain real-time events occur 
(the computer then returns to the interrupted BASIC program). All this, 
coupled with the speed of an extended Microsoft BASIC running on a 16-bit 
machine, makes the IBM Personal Computer an excellent gaming device. Since 
the BASIC is very fast by 1 current standards, IBM Personal Computer owners 
will be able to write rather interesting graphics games without leaving BASIC I 

Multiplayer Games 

I think there's a large market for multiplayer games. Two-player games are 
fine, but it's really fun to get a group of people together for an exciting game. I 
realized this while playing some two- and four-player video games on the 
Atari Video Computer System (the game cartridge system, not the microcom- 
puter). Even though the games were simple, it was a lot of fun to be playing a 
game with three other people. 




New! Z Controller and Z Drives 



Expect more from Percom. You won't be disappointed. 



Percom's double-density Z Controller for the H-89 is 
now available. Besides its many outstanding drive 
control features, the Z Controller includes a bonus 
parallel port that lets you directly connect your com- 
puter to a standard, off-the-shelf Epson MX-80, Oki- 
data Microline 80 or other low-cost printer. 

• Controls up to four single- or double-headed mini-disk drives. 

• Handles 35-, 40-, 77- and 80-track drives, and other standard 
track densities. • Formatted data storage capacity of 80-track dis- 
kettes is over 368 Kbytes. Forty-track diskettes store over 184 
Kbytes. Capacities for other track densities are proportional. A Z 
system with four double-headed, 80-track drives provides almost 
3 megabytes of on-line data. • The Z Controller co-resides with 
your H-89 disk drive controller. Your software can select either, 
and you don't have to move drives around when switching be- 
tween systems. • The Z Controller includes Percom's proven dig- 
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circuit. Expect reliable disk operation for a long, long time under 'Z' 
control. • The Percom Z Controller is priced at only $249.95, com- 
plete with HDOS-compatible disk drivers on diskette, internal inter- 
connecting cable and comprehensive users manual. 

System requirements - H-89 Computer with 24 Kbytes memo- 
ry (min), Replacement ROM Kit H-88-7 and HDOS 2.0. 



Add-On Z Drives for H-89, H-8 Computers 

• Forty- and eighty-track densities in either 1- or 2-drive modules. 

• All drives are rated for single- and double-density operation. With 
a Z Controller, an 80-track drive can store over 364 Kbytes (for- 
matted, one-side), a 40-track drive can store over 184 Kbytes. 

• Some models permit "flippy" storage, letting you flip a diskette 
and store files on the second side. • Z drives are fully tested, includ- 
ing a 48-hour operating burn-in to prevent shipment of drives with 
latent defects. • Assembled and tested one-drive units from only 
$399, two-drive units from only $795. 

System requirements - H-89 or H-8 computer with 16-Kbyte 
RAM, Heath first-drive floppy disk system, HDOS and drives inter- 
connecting cable. (Two-drive interconnecting cable optionally 
available from Percom) 

PRICES AND SPECIFICATIONS SUBJECT TO CHANGE WITHOUT NOTICE. 

Watch for announcement of 'Z' CP/M. 




PERCOM DATA COMPANY, INC. 

1 1220 PAGEMILLRD. DALLAS. TX 75243 
(214) 340-7081 

ToWFree Order Number: 1-800-527-1222 



£ WK1 PERCOM DATA COMPANY. Inc. 

PERCOM. ZFD 40 and ZFD-81) are trademarks ol Percom Data Company. 

CP/M is a trademark of Digital Research Corporation. 



Yes ... I'd like to know more about Percom Z drives and the 
Z Controller. Rush me free literature. 

Send to 

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V^ Ithaca Intersystems Inc. 

Micros for bigger ideas. 

Ithaca Intersystems Inc. 

1650 Hanshaw Rd • Ithaca, NY 14850 • TWX 510 255-4346 
U.K. Distributor: 
Ithaca Intersystems (U.K.)Ltd. 

Coleridge Road London N8 8ED Phone: 01-341 2447 Telex: 299568 




Editorial. 



Certainly one of the most engaging and innovative 
games produced in the last year or so is Timothy Smith's 
Olympic Decathlon, distributed by Microsoft Consumer 
Products (see page 74 of this issue). Not only are the 
graphics overwhelming and the idea clever, but the in- 
volvement of up to eight people in Decathlon's ten 
athletic events makes it a great party game. Even though 
only one or two people are actively participating at once, 
the game is interesting to watch, and everyone wants to 
see how the new player affects the cumulative ratings. 
Olympic Decathlon is the first true party game for 
microcomputers, but I'm certain it won't be the last. 

Microcomputers and War Games 

"War gaming," which usually calls to mind historical 
simulations with maps laid out on a hexagonal grid and 
plenty of cardboard playing pieces, is an area that is beg- 
ging for the assistance of microcomputers. Many of us 
have tried war games and have balked at the hundreds of 
cardboard counters, the long and often unclear rule 
books, and the tedious resolution of combat through dice 
rolls and large tables. With microcomputers we can 
eliminate (or at least lessen) these problems; they can also 
do things never before possible with conventional war 
games. 

Another advantage microcomputers can bring to war 
gaming is the ability to give each player only partial (or 
even misleading) information about troop positions and 
other aspects of the game. (This is in contrast with the 
complete information conveyed by having the game 
board and pieces in full view, as is done in most war 
games.) Microcomputer-based war games also provide a 
fairly intelligent enemy for solitary play. 

Microcomputers are beginning to be taken seriously by 
war game producers. Several programs help ease the 
more tedious and time-consuming portions of existing 
war games; these do not replace the map-and-cardboard- 
counters game but are used to make play easier and 
faster. Avalon Hill, the company that started war gaming 
as we know it in the late 1950s, now offers a line of 
microcomputer games, some of which have military 
themes. Although these can't be called war games as 
such, Avalon Hill's entry into the microcomputer game 
market is important, and I'm sure that the company will 
make additional, more successful entries into the market. 

Simulations Publications, Incorporated (SPI), which 
publishes the leading American war-gaming magazine, 
Strategy and Tactics, is also showing some interest in 
microcomputers. As this article is going to press, SPI is 
advertising for a microcomputer programmer /war- 
gamester for their staff. Their magazine on game design, 
Moues, occasionally contains microcomputer game 
reviews and speculations on the future of war gaming. 
(For people like me who can't get interested m historical 
war gaming, SPI also publishes Ares, a magazine that 
deals with science-fiction gaming. Like Strategy and Tac- 

Clrcle 203 on Inquiry card. 




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Editorial. 



tics, each bimonthly issue contains a complete game. 
SPI's address is 257 Park Ave S, New York NY 10010; 
Avalon Hill's address is 4517 Hartford Rd, Baltimore MD 
21214.) 

A very interesting computer war game is Chris 
Crawford's Eastern Front (1941), mentioned in this issue's 
'The Coinless Arcade," page 36. Apart from its excellent 
graphics, the computer automatically takes care of all 
movement and combat calculations — you just make your 
moves and await the consequences. Not only is this a lot 
more fun (for me, at least), but it also brings war gaming 
closer to the experiences of the generals who fought the 
original battles. 

Mixed-Media Games 

Using microcomputers to assist in playing a conven- 
tional war game reminds me of a new kind of game that is 
beginning to appear. The mixed-media game uses a 
microcomputer (or a hand-held unit with a microproces- 
sor in it) to control or influence a board game of some 
sort. 

Two new arrivals to the mixed-media format are 
Milton Bradley's Dark Tower and Mattel's Dungeons and 
Dragons. In Dark Tower, the microcomputer is housed in 
a black plastic tower that dominates the center of the 
board. It can be turned toward one player at a time to 
give exclusive information regarding the player's quest to 
retrieve a magic scepter. In Dungeons and Dragons, a 
microprocessor housed beneath a chess-like game board 
randomly generates a maze and gives players audible 
clues in their search for a dragon's treasure. 

A third mixed-media game is of interest here because 
its microprocessor is in a unit that is closer to a full micro- 
computer. The Quest for the Rings is a board-and-car- 
tridge game used with Magnavox's Odyssey 2 video game 
system. The Odyssey 2 system relies on interchangeable 
cartridges for video games but includes a touch-sensitive 
keyboard in standard typewriter layout. Although I've 
only seen the packaged unit in a store, I get the impres- 
sion that most of the action takes place on the video 
display, while the board, a map of an imaginary world, is 
used to chart the game's progress. This is an exciting 
development because it combines a conventional board 
setting with the real-time action of a video game, com- 
plete with sound, color graphics, and the manual dexteri- 
ty such a game requires. 

In all these cases, the computer is more than simply a 
game aid — it is a unique part of the game that incor- 
porates otherwise-impossible elements. The computer 
can supply an unknown intelligence that guides the game 
and can often adapt to players of varying skill, but it can 
also provide color, sound, graphics, and interaction 
through novel forms of input and output (eg: light pen, 
joystick, music synthesizer, etc). 

There's no doubt that mixed-media games possess 
tremendous potential. As microcomputer game manufac- 



turers keep striving for something new to offer the mar- 
ket, I'm sure we'll have computer-based board games in 
the next year or so. (Another reason these games will be 
attractive to manufacturers is that the necessary physical 
components of the game — board, playing pieces, rule 
book — make software piracy less attractive to the poten- 
tial pirate). 

What of the future? It's limited only by the imagination 
of inventors. I'm sure you've thought of an augmented 
video game that puts the player inside a "space capsule" 
and heightens the sensation of space flight by tilting or 
vibrating the capsule. An ambitious microcomputer hob- 
byist or club could build something like that. Laser video- 
discs or videotape recorders could add even more 
realism. In games yet to come, you might be participating 
in scenes like those of Star Wars or Dragonslayer — who 
knows? 

Such games are not far off. Rod Daynes of the Univer- 
sity of Nebraska's Videodisk Design /Production Group 
is working on an adventure game that helps deaf children 
learn basic coping skills. In one such game, a child is 
asked to solve a mystery. Through the use of multiple- 
choice questions superimposed on the video display, the 
child is led through a decision tree of over 160 nodes. 
Each node is not merely a static picture — it's a moving 
image with sound I 

A Call for Imagination 

As I look at the stunning video games and new micro- 
computers that have even more capabilities than previous 
machines, I dream of the games we'll be playing two or 
three years from now. But is bigger and more sophisti- 
cated the only new direction we have? A good graphics 
game takes several months to write, and the complexity 
of the required effort discourages many of us from trying 
to write one. I've been working on an arcade-like game 
for several months now, and I feel that the satisfaction I'll 
get from seeing the game work is small compared to all 
the months of drudgery I've put myself through. In fact, I 
feel more like a project manager than a hobbyist. 

Because of this, I think it should be said that games do 
not have to be complicated to be fun. Many people enjoy 
adventure programs, and the best ones are still text-only. 
But the problem is this: it's always easier to implement an 
existing idea than to create a new one. 

This brings me to the BYTE Game Contest (see page 
302). Here is a chance for you to share your creative 
efforts with the rest of our readers. Even if you have only 
a little time to spend on programming, you may come up 
with that simple but fun game that proves irresistible. 
Simple or sophisticated, the most important thing is "Be 
original I" We can't wait to see what you're going to come 
up with.B 



10 December 1981 © BYTE Publications Inc 



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Circle 27 on inquiry card. 



Letters 



Benchmark Flawed 

Ithaca Intersystems Inc is the vendor of 
the Pascal/Z compiler. We have just re- 
ceived a copy of the September 1981 
BYTE and are quite concerned with Mr 
Jim Gilbreath's article "A High-Level Lan- 
guage Benchmark" (see page 180). Since 
we have no basis for comparison of other 
high-level languages, we do not dispute 
Mr Gilbreath's results in benchmarking 
these, but we do wish to criticize his 
testing of Pascal implementations. 

First, Mr Gilbreath could not have run 
the Pascal program given in his article 
under Pascal/Z because it uses the non- 
standard FILLCHAR construct, which we 
did not implement in Pascal/Z as it is not 
part of either the Jensen and Wirth defini- 
tion of the language or of the proposed In- 
ternational Standards Organization stan- 
dard. We have seen this program before in 
a benchmark performed and publicized by 
MT Microsystems. We feel that the use of 
this program, when taken with the 
"special thanks" to Mike Lehman, the 
author of Pascal/MT+, cannot by any 
stretch of the imagination be viewed as 
objective. If you are testing a high-level 
language compiler against other imple- 
mentations of the same language, it seems 
only fair that the program tested under 
each implementation is identical to that 
tested under the others. 

Second, no information is given regard- 
ing testing conditions. Most compilers of- 
fer a number of checking features that 
have varying defaults. Mr Gilbreath gives 
extremely little specific information re- 
garding the status of these options. 

Third, no version numbers are given for 
any of the software except BD Systems' C. 

Fourth, Mr Gilbreath fails to mention 
that not all of the implementations he 
tested were true compilers. Several were 
p-code versions that require an inter- 
preter. Additionally, the Pascal Micro- 
engine and Pascal 100 are machines that 
accept p-code as their native "assembly 
language." 

Fifth, our company was not included in 
the vendor address list on page 198, 
although most other software vendors 
(and all other microcomputer software 
vendors) mentioned in the article were. 

We feel that one test does not constitute 
a benchmark. We have spent a great deal 
of time conducting our own benchmarks 
on our compiler and on MT Microsys- 

14 December 1981 © BYTE Publications Inc 



terns' Pascal/MT+. The results prove 
that our product is far superior to MT + , 
which we consider to be our closest com- 
petition. Copies of these reports are 
available to the public. 

In conclusion, we would like to quote 
from a letter we received recently from Mr 
Peter Grogono, author of Programming 
in Pascal (Reading MA: Addison-Wesley, 
1978). He is a Pascal/Z user: 

. . . / am very pleased with Pascal/Z 
and have used it extensively in my re- 
cent work. To the best of my knowl- 
edge, it is the highest quality Pascal 
compiler available to users of micro- 
processors. . . . 

We welcome questions from BYTE and 
its readers because we are very anxious to 
dispel the negative effects of Mr 
Gilbreath's article. 

Laurie Hanselman, Software Products 

Manager 
Ithaca Intersystems Inc 
1650 Hanshaw Rd, POB 91 
Ithaca NY 14850 

Jim Gilbreath Replies: 

There has been a surprising amount of 
interest shown in the benchmark article. I 
have received at least 30 telephone calls 
and so many letters that it is beyond my 
ability to respond to each individually. So 
far, all the letters but Ithaca Intersystems' 
have been complimentary and many have 
supplied additional timing data on other 
languages and computers, such as the 
CRAY-1 supercomputer, that I did not 
test. 

In the article, I was careful to point out 
(on page 198): ". . . to the software sup- 
pliers who are upset because I didn't use 
the latest and greatest version, I 
apologize: I had to use what was avail- 
able. " My article was not a commissioned 
assignment for BYTE. It was simply a 
computer experimenter's report of his ex- 
periences collecting data in a "fun" project 
for presentation at the local computer 
club. The data were collected over a nine- 
month period whenever an opportunity 
presented itself. It was another seven 
months before the article appeared in 
BYTE. 

Much of the data was obtained in com- 
puter stores and in conference exhibition 
environments before I ever thought of 
writing a magazine article. Pascal/Z was 



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Letters ' 

tested using an early version in a com- 
puter store, and I am certain Ithaca Inter- 
systems now has a greatly superior model. 
As I recall, it was necessary to assemble 
the entire library along with the compiled 
code on that version. I was unable to run 
the benchmark on a later version of 
Pascal/Z at Ithaca Intersystems' booth at 
the Anaheim National Computer Confer- 
ence exhibit. 

There were several slightly different 
versions of the benchmark program in all 
of the languages, but only one was printed 
for each case to save space. FILLCHAR 
was used in Pascal/ MT+ because it was 
there and it corresponded to the ARY5ET 
function in the ZSPL language that was 
used as the teaching tool. Other Pascal 
versions used a FOR statement. The dif- 
ference was not major (e.g., about 3 sec- 
onds for MT+). 

This program has been used in bench- 
marks publicized by MT Microsystems 
and also Digital Research, as Miss 
Hanselman indicated. But they copied it 
(with permission) from me, not the re- 
verse. The "special thanks" given to Frank 
MacLachlan, Mike Lehman, and Pete 
Ridley referred to their encouragement to 
submit the data for publication following 
the computer society meeting and to their 
help in obtaining some of the assembly- 
language timing data on processors such 
as the 68000. I must respectfully disagree 
with the contention regarding loss of ob- 
jectivity. 

I regret that I cannot say what specific 
version of Pascal/Z was used. It was 
tested well over a year ago, and I am 
guilty of forgetting to write down the ver- 
sion number. There are several other in- 



stances where data are missing that could 
have been collected with more time avail- 
able on the system. It is indeed unfor- 
tunate that Pascal/Z's options default to 
ON, because I used the products pretty 
much as they "came out of the box. " 

I agree with Miss Hanselman's point 
that the Microengine and the Pascal 100 
are hardware interpreters. In response to 
Ithaca Intersystems not being mentioned 
in the list of vendors, the list was added 
by the BYTE editors, and I only supplied 
the addresses I was asked for. Regular 
BYTE advertisers, such as Ithaca Intersys- 
tems, were supplied by the editors. 

I am sorry if my article has damaged 
Ithaca Intersystems' market. That was not 
my intent, but I did point out at the begin- 
ning and the end of the article that one 
benchmark does not tell the whole story. 

OH Drilling: Nyet 

Readers of the September 1981 BYTE 
may be interested in the following secret 
communication regarding artificial in- 
telligence. 

General Petr Ivanovich Ivashutin 
Glavnoe Razvedyvatelnoe Upravlenie 
Dzerzinsky Square 
Moskva 

Comrade, 

Important info about British North 
Sea oil-drilling platforms. September 
1981 BYTE, page 262, reports that one 
Donald Michie is working on artificial 
intelligence program "to diagnose 
operating problems on North Sea oil 
platforms" (see "Knowledge-Based Ex- 
pert Systems Come of Age," pages 238- 



281). Same BYTE issue reports on page 
200 (see "Science Fiction's Intelligent 
Computers," pages 200-214) about "an 
article in Scientific American that 
describes 1iow to teach a matchbox to 
play tic-tac-toe.'" Diligent search 
reveals that mentioned article is Mar- 
tian Guarder's column "Mentalmagical 
Games" in the March 1962 Scientific 
American, page 138. Note good that 
creator of matchbox tic-tac-toe is same 
British genius Donald Michie ("Trial 
and Error," Penguin Science Survey 
1961, vol. 2) as is hopping around 
North Sea oil platforms. Donald 
Michie easy to spot, is always carrying 
300 coded matchboxes filled with rat- 
tling colored beads. 

Conclusions: British is not drilling 
for oil in North Sea, but rather is play- 
ing huge tic-tac-toe game with oil- 
drilling platforms. 

Yours, 

Boris Goofitup 

PS: Above correlation discovered by 
using Knowledge-Based Expert System 
on Moskva Center supplied 1-bit par- 
allel processor. Please requisition 
"carry bit" circuit as I getting aching 
eyes watching for overflow bit. 

This message was intercepted in early 
September on a Drake short-wave re- 
ceiver using a tracking variable-frequency 
detector and a Fast Fourier Transform 
speech desynthesizer. 

Dr John E Shively 
404 Plymouth Court 
Benicia CA 94510 



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16 December 1981 © BYTE Publications lnc 




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Letters. 



Knowledge, Ethics, and Piracy 

I was not moved to respond to Chris 
Morgan's editorial on software piracy (see 
"How Can We Stop Software Piracy?" 
May 1981 BYTE, page 6), but having read 
the wave of letters in the September 1981 
BYTE, I feel one point of view has been 
missed. 

A few hundred years ago, before print- 
ing was invented, bands of monks pains- 
takingly copied manuscripts by hand to 
pass knowledge and learning to others. 
These documents were closely guarded 
and available only to the rich. 
"Education" existed only in these 
monasteries and for the elite. 

After the invention of the printing press 
with movable type, books became less ex- 
pensive and easier to duplicate. Learning 
filtered down to the "middle classes." 

Somewhere in our social development 
we realized that the impoverished masses 
had not received the benefits of learning, 
and the free lending library evolved. 

The author of a novel gets paid by the 
publisher, who happily sells to both the 
bookstore and the library. If I own a book 
and a friend wants to borrow it, I lend it 
and, in so doing, deny the publisher a 
sale. Society does not condemn either of 
these actions. But the authors of software 
would have us believe these acts are 
felonies when extended to their product. 
Our attitude toward literature is mature, 
but our feelings are "monastic" toward 
software. 

Of course, there is a distinction. When 
a book is borrowed, the recipient has tem- 
porary use and returns the original. No 
copy is made. If it is a reference book, the 
user may buy his or her own or copy a 
few pages. One is more likely to purchase 
paperbacks than to make copies. 

Extending this analogy then, what is 
needed are plentiful, inexpensive libraries 
of software for the impoverished masses 
to borrow and return. Couple this with in- 
expensive originals, analogous to paper- 
backs, and the problem could be solved. 

Martin Oakes 
2100 Oriole Dr 
Freeport IL 61032 



There have been many discussions 
recently in BYTE regarding the problem of 
program theft. In many jurisdictions this 
theft becomes a felony because of the 
value of the product stolen. 



In the discussions regarding this prob- 
lem, the primary thrust seems to be tech- 
nological means to render theft extremely 
difficult. But it seems to me that the pri- 
mary cause is of a social nature. For at 
least two decades, the philosophy that 
crimes against property — i.e., crimes that 
do not physically harm people — are of no 
consequence has been part of the changing 
social fabric of this and other nations. 

The most effective solution to this prob- 
lem would be a demand that the educa- 
tional establishment return to the tradi- 
tional teaching of morals, ethics, and 
responsibility that prevailed prior to the 
embracing of what is now proven to be a 
fallacious theory. All crimes do hurt all 
people. 

By concentrating only on technological 
solutions to complex problems that in- 
volve social aspects of the world in which 
we live, we technologists do ourselves and 
the general population a disservice. 

Finally, it seems to me that BYTE might 
well emulate Quality magazine by inviting 
commentary from social scientists as was 
done in its September 1981 issue. 

Walter D Nichols, President 
YES Computer Sciences Inc 
3090 Acushnet Ave 
New Bedford MA 02745 



More Intelligent Computers 

I'd like to comment on Donald Byrd's 
article "Science Fiction's Intelligent Com- 
puters." (See the September 1981 BYTE, 
page 200.) I have been a science fiction 
fanatic for most of my life and am espe- 
cially interested in computer-related 
stories. 

I credit my interest in computers and 
science fiction to one story that Mr Byrd 
overlooked, "The Moon Is a Harsh Mis- 
tress," by Robert Heinlein. This story is 
possibly the earliest tale of its type. 
Heinlein is vague about the origin of the 
intelligence (named "Mycroft," after 
Sherlock Holmes' "Smarter Brother"), but 
he is quite accurate about its capabilities. 
I'm surprised that Byrd did not mention it. 

In Byrd's subsection called "The 
Adolescence of P-l," he does not mention 
that Greg Burgess endows P-l with two 
very human emotions: fear and hunger. 
Hunger is the "primary" emotion, being 
the quest for more and more storage. The 
fear element is that P-l constantly looks 
to see if it has been detected. I would 
credit these emotions as responsible for 



18 December 1981 © BYTE Publications Inc 



Circle 288 on inquiry card. 










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Letters . 



P-l's development of intelligence. One 
thing to note is that P-l was written in 
PL/I, and 800,000 lines of code (Byrd's 
figure) in PL/I can go a long way. 

Some other works that contain in- 
telligent computers are the book Man 
Plus, by Fred Pohl, and the movies Col- 
ossus: The Forbin Project and Demon 
Seed. 

All in all, Mr Byrd wrote an excellent 
article for an excellent magazine. 

Dana W Cline 
4725 S Lowell #18 
Littleton CO 80123 



No Mincing of Words 

Thank you, BYTE and Christopher O 
Kern, for a factual, straightforward 
review of the MINCE text editor. (See 
"MINCE, A Text Editor," September 1981 
BYTE, page 150.) In response to earlier 
suggestions from users, MINCE 2.6 now 
runs the redisplay three to five times faster 
than the version that was reviewed and 
found to be flawed in this respect. 

Additionally, source code (in C) is now 
included with MINCE. The price has been 
changed to $175. 

Brian N Hess 

Mark of the Unicorn 

POB423 

Arlington MA 02174 



One Club Too Many 

Somehow our organization has been er- 
roneously listed in BYTE as being a com- 
puter club. I'm not sure of how or why 
this happened, but we get several calls and 
letters per month of inquiry. 

Culpepper and Associates is a manage- 
ment-consulting organization that sup- 
ports vendors of large software products. 
While we publish a newsletter, Salt 'n 
Pepper, it would not be of interest to 
BYTE readers and we provide no services 
that the typical reader of BYTE would be 
interested in. 

Warren L Culpepper, President 
Culpepper and Associates Inc 
4922 Heatherdale Ln 
Atlanta GA 30360 



Indexing Your BYTEs 

As a professional small-computer user, 
I find BYTE magazine a source of varied 
technical and product information, as it is 
intended. Unfortunately, accessing a par- 
ticular article can be quite a chore when I 
need to refer to a large stack of BYTEs. It 
would certainly enhance the magazine if a 
cumulative index extending back 48 
months were to be provided. An ideal ex- 
ample of this can be found in Consumer 
Reports magazine, published by Con- 
sumers Union, Mount Vernon, New York. 

It would be helpful if a code could be 
added to each article title indicating the 
computer and programming language 
referred to in the story. It would also be 
great if the programs listed in BYTE were 
available on tape or disk at a nominal 
charge. 

Gary Oppenheimer 

79th Street Boat Basin, #39 

New York NY 10024 

We have received many requests similar 
to yours. As a result, we present a 
cumulative index to BYTE in this issue. 
Unfortunately, producing tapes and disks 
in the myriad formats in use today is an 
expensive proposition; however, we do 
encourage authors to attempt to provide 
this service for our readers. . . . CPFB 



BYTE's Bits 



National Leaves 
Bubbles Behind 

National Semiconductor Corporation is 
withdrawing from the bubble-memory 
business. According to Charles E Sporck, 
president and chief executive officer, the 
move comes because of a period of slow 
semiconductor business activity. To keep 
spending in line with sales, and because 
the bubble-memory business is not pro- 
jected to reach previously anticipated 
levels, National is discontinuing produc- 
tion of bubble-memory devices. For- 
tunately for users of National devices, 
Motorola will make bubble-memory parts 
using National's specifications. 

Earlier this year, Rockwell Internation- 
al and Texas Instruments gave up on bub- 
ble memory, citing similar reasons. At this 
point, Intel Corporation and Motorola 
are the sole American bubble-memory 
manufacturers. ■ 



December 1981 © BYTE Publications Inc 



Peachtree Software says, Pardon us for being so 

INDEHISCENT 



Did you know that the peach, that delicious 

and succulent fruit borne on a drupiferous 

tree, is an indehiscent fruit? 

In fact, the peach is classified 

as being "fleshy indehiscent." 

Perhaps that's why most 

peaches seem to be blushing. 



A oo many software users go all to 
pieces. And it's easy to understand 
why. Even the most mature indi- 
viduals can come apart at the seams, 
trying to master the variety of dif- 
ferent instructional formats with 
off-the-shelf software. Peachtree 
Software's documentation and user 
manuals are so simplified that it's 
downright indehiscent! With the 
same easy-to-use fotmat package 
after package — you'll eat 'em up 
like peaches and cream. And that, 
in turn, will do wonders for your 
nervous system. 




Actually, there is nothing naughty or reveal- 
ing about being indehiscent. (Sorry, fellas. ) 
It simply means that the 
peach doesn't burst open 
when it is mature. And that's 
nice. It certainly makes har- 
vesting a lot less messy. 



Payable, Inventory, Mailing List, 
Payroll, and Magic Wand. 



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de variety of packages, all 
from the same Tree. The "one 
source" advantage becomes increas- 
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system. And the Tree is loaded with 
a great variety of time-tested busi- 
ness software. Here's just a sample. 
Magic Wand™ -With this ex- 
tremely popular word processing 
system, a minimum of commands 
perform basic functions. It's re- 
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The Peachtree Series 40 is 
adapted for the Apple II 's standard 
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The series includes General Ledger, 
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t takes time to grow a tree and 
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That's why Peachtree business 
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Trust the Tree for Unsurpassed 
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That's why there are over 20,000 
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**Microsoft is a trademark of Microsoft Consumer Products, Inc. 'Apple II is a trademark of Apple Computer, Inc. 



Circle 341 on inquiry card. 



BYTE December 1981 



23 



Software Review 



Robotwar 



Curtis Feigel, Technical Editor 



"Welcome to the battlefield of the future!" seemed to 
me a rather ominous greeting. I had opened the Robot- 
war instruction manual expecting to educate myself 
about robots through experimentation. Instead, I was 
reading about sometime after the year 2002 AD, when in- 
ternational conflicts are resolved through robot warriors. 
In addition to its gaming aspect, Robotwar provides 
those interested in robotics with an off-the-shelf simula- 
tion for developing practical robot software when no 
robot actually exists. 

Robotwar falls into the realm of multimachine games, 
where the computer is not an adversary but a vehicle for 
two or more humans to compete in a manner that would 
otherwise be impossible. (You certainly couldn't build an 
armored computer on tracks and program it to fire ex- 
plosive shells for $39.95.) 

Games for More Than One Person 

In "Multimachine Games" (see the December 1980 





Name 


Language 


Robotwar 


Applesoft BASIC 


Type 


Computer 


Programming game 


Apple II with 48 K bytes of 




memory and Applesoft 


Manufacturer 


ROM 


Muse Software, Inc 




330 N Charles St 


Documentation 


Baltimore MD 21201 


75-page booklet 


(301) 659-7212 






Audience 


Price 


People interested in pro- 


$39.95 


gramming or robots 


Format 




5-inch floppy disk for both 




Apple DOS 3.2 and DOS 




3.3 





BYTE, page 24), Ken Wasserman and Tim Stryker iden- 
tified three factors that make games fun: 

• More than one human player is involved. 

• Success in the game hinges on proper application of 
available information. 

• The major constraints are not the game rules but the 
player's fleetness of mind and hand. 

Like football and some other popular sports, Robotwar 
embodies all three quite fully. 

As many as five robots can be placed in the Robotwar 
arena simultaneously; each robot is identical but for the 
program you provide. The arena is a 256 by 256 meter 
square with impregnable walls; spectators view from 
above. The game's main menu (see photo 1) allows the 
user to start a battle, schedule a series of matches, and 
edit and test a robot's program. While the robot is in the 
arena, its program is in complete control. There is 
nothing you can do but watch from above. 

Perhaps the most remarkable aspect of this game is 
that, unlike chess, playing against yourself can be fun. As 
the programmer, your robot creation (and a little bit of 
you) is in the arena and lives or dies as a result of your 
analysis of the problems involved. One robot may fall 
prey to another, but it is the programmer who vicarious- 
ly feels the pain, even if one person programmed both. 

Programming for War 

The robots themselves can be imagined as consisting of 
a square chassis with powered, tank-like treads. The 
chassis is equipped with a gun that swivels 360 degrees 
and a narrow-beam radar unit that swivels to detect walls 
and other robots. Of course, a computer is located some- 
where within the armored hull. Each of these components 
has a few interesting features that make programming the 
robot a challenge, and some trial-and-error work is in- 
volved. 

Each robot's computer has 24 general-purpose storage 
registers and 10 control registers (see table 1). The stor- 
age registers are referred to by letter of the alphabet and 



24 December 1981 © BYTE Publications Inc 



Circle 267 on inquiry card. 



ui' r* 



ilium 



la 1 



1 1 ^M 



--■1 C.r '*i----» f-i' 






nk - 1 




Turn your Apple into the world's 
most versatile personal computer. 



The SoftCard™ Solution. SoftCard 
turns your Apple into two computers. 
A Z-80 and a 6502. By adding a Z-80 
microprocessor and CP/M to your 
Apple, SoftCard turns your Apple into 
a CP/M based machine. That means 
you can access the single largest body 
of microcomputer software in exist- 
ence. Two computers in one. And, the 
advantages of both. 

Plug and go. The SoftCard system 
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Just plug it into any slot (except 0) of 
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SoftCard supports most of your Apple 
peripherals, and, in 6502-mode, your 
Apple is still your Apple. 

CP/M for your Apple. You get CP/M 
on disk with the SoftCard package. It's 
a powerful and simple-to-use operating 
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versatility of the SoftCard/Apple. 



BASIC included. A powerful tool, 
BASIC-80 is included in the SoftCard 
package. Running under CP/M, ANSI 
Standard BASIC-80 is the most 
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available. It includes extensive disk I/O 
statements, error trapping, integer 
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sive EDIT commands and string func- 
tions, high and low-res Apple graphics, 
PRINT USING, CHAIN and COM- 
MON, plus many additional com- 
mands. And, it's a BASIC you can 
compile with Microsoft's BASIC 
Compiler. 

More languages. With SoftCard and 
CP/M, you can add Microsoft's ANSI 
Standard COBOL, and FORTRAN, or 



Basic Compiler and Assembly Lan- 
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Seeing is believing. See the SoftCard 
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Complete information? It's at your 
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SoftCard is a trademark of Microsoft. Apple II and 
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Inc. CP/M is a registered trademark of Digital 
Research. Inc. 




CONSUMER^ PRODUCTS 



Microsoft Consumer Products, 400 108th Ave. N.E., 
Bellevue. WA 98004. (206) 454-1315 



are employed in a manner similar to variables in BASIC 
and other high-level languages. The control registers are 
referred to by function name and either control some 





HHAT 00 YOU MftHT TO 00 HOW? 


1. 


START ft ROBOT BATTLE 


2. 


ASSEMBLE OR TEST A ROBOT 


3. 


EDIT ROBOT SOURCE C00E 


4. 


SWITCH SOUND (HON OH) 


5. 


HAKE ROBOT STORAGE DISKS 


6. 


EXIT TO APPLESOFT BASIC 


7. 


SCHEOULE AH AUTOMATIC MATCH 


8. 


RUN A SCHEDULED MATCH 



Photo 1: The game's main menu. Playing Robotwar isn't simply 
a matter of starting a battle. A robot's program must first be 
written, assembled, then tested and debugged before a series of 
matches can be scheduled. Some menu selections, such as "2" 
(exit to the assembler), respond with a submenu — the game is 
mostly menu-driven. 



robot function or provide information from sensors. 
(There is also an indexing scheme that could make for 
some very sophisticated programs.) 

Motion is controlled by storing numbers in the 
SPEEDX and SPEEDY registers. These registers set the 
robot's speed in the east/west and north/south directions 
respectively and show the robot's current position within 
the arena. Maximum speed is obtained when the value 
255 or —255 is placed in the registers, with sign in- 
dicating direction. Of course, the robot has mass and in- 
ertia, so it's always necessary to allow for acceleration 
and deceleration times in your programming. 

To fire the robot's gun, first store a degree value in the 
AIM register to swivel the gun. When a distance value is 
sent to the SHOT register, the gun is fired, and the shell 
explodes at the distance set. After a shot, the gun must be 
allowed to cool. When the temperature reading stored by 
the gun mechanism in the SHOT register reaches zero, 
the gun is ready to fire again. 

The radar unit sends out a narrow-beam pulse when a 
degree value is stored in the RADAR register. The value 
returned in the register indicates the distance to a detected 
object. If the value returned is positive, the object is a 
wall. If it is negative, the object is a robot. By first detect- 
ing another robot with the radar and then transferring the 
position and distance information to the AIM and SHOT 
registers, your robot can intelligently seek out and 
destroy other robots. 




THE CAT'S-EYE VIEW 

Get a lion's share of graphic capabilities 
at a price that will make you purr. 

CAT digital graphic systems interface with S-100, PDP-11, LSI-11 and other host 
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• Flash digitizer to grab your image from camera, broadcast or recording in as 
little as 1/60 of a second. 



• Highest possible resolution— up to 484x512x8, 242x512x16 or 242x256x24. 

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• Light-pen input and other useful options. 

• Flexibility to fit your computer imaging needs within the 
CAT-100 through CAT-800 and CBX series. Call us for a 
CAT that suits your application . . . and your budget. 



MM DIGITAL GRAPHIC SYSTEMS, INC. 

935 Industrial Avenue, Palo Alto, CA 94303 
Call (415) 856-2500 



26 December 1981 © BYTE Publications Inc 



Circle 123 on Inquiry card. 



Circle 25 on inquiry card. 



Take a look at our EPROM blaster 
for your Apple" or TRS-80; 







Apparat announces the most 
versatile EPROM burner available 
today for your TRS-80 model I and 
III or Apple computer ... the 
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The A.P.B. system will program all 
commonly used 24 pin EPROMs by 
using special personality modules 
that adapt the unit to the EPROM. 
The following EPROMs are 
programmable: 2704, 2708, 2716, 
(3-volt) & (5-volt), 2732, 2508, 2516 
and 2532. 

The versatility and power of the 
A.P.B. system means you're getting a 
PROM burning package with 
extensive capabilities. The price, 
$149.00, insures you're getting the 
most cost-effective PROM burner on 
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With a unique combination of 
personality modules and 



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sophisticated software, A.P.B. 
will perform many operations 
impossible with conventional 
PROM burners. Mere's a brief 
list of some of A.P.B. 's capabilities: 

• Verify ROM is erased 

• Read ROM 

• Copy ROM 

• Copy between different ROM types 

• Program ROM 

• Partial programming and copies 

• Verify programming 

• Read or save ROM data on disk or 
cassette (Apple only) 

• Program directly from computer 
memory 

■ Examine and/or modify working 
memory 

• Preset working memory 

The A.P.B. system is the most 
flexible PROM burner available. The 
A.P.B. system package consists of an 
interface card that plugs directly into 
an expansion slot*, a complete set 




of personality modules, software on 
disk and a detailed instruction 
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MEWDOS/80, or TRSDOS™ for the 
TRS-80, and APPLE DOS™ or APEX 
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If you're looking for a powerful, 
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inquiries welcome. 

(303) 741-1778 

TRS-80 version requires the TRS-80 bus 
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TR5-B0, and Apple are trademarks of Tandy Corp. 
and Apple Computer. 



Apparat, Inc. 



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"O/Y GOIHG SUPPORT FOR MICROCOMPUTERS' 




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DIAGNOSTICS 

Diagnostics II is SuperSoft's expanded 
Diagnostic package. 

Diagnostic II builds upon the highly acclaimed Diagnostics 
I. It will test each of the five areas of your system: 



Terminal 



Memory 



Printer 



CPU 



Disk 



Every test is expanded. 



Every test is "submit"-able. A "submit" file is included 
in the package which "chains" together the programs in 
Diagnostics II, achieving an effective acceptance test. All 
output can be directed to a log file for unattended 
operation, for example over night testing. Terminal test is 
now generalized for most crt terminals. A quick-test has 
been added for quick verification of the working of the 
system. 

The memory test is the best one we have encountered. It has 
new features, including: 

• default to the size of the CP/M Transient Program Area 

• printout of a graphic memory map 

• bank selection option 

• burn in test 

• memory speed test 

Diagnostics-ll includes the only CPU test for 8080/8085/Z80. 

A Spinwriter/Diablo/Qume test has been added, which 
tests for the positioning and control features of the Spin- 
writer/Diablo/Qume as well as its ASCII printing features. 
(Serial Interface only) 

And, as with all SuperSoft products, a complete online HELP 
system and user manual is included. 

Price: $100.00 (manual only): $15.00 

Requires: 32K CP/M Software available lor virtually all CP/M 

systems. Specify your system. 



Available from fine dealers everywhere, 

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SUPERSOFT ASSOCIATES 

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You can check on any damage to your robot via the 
DAMAGE register. This contains the percent damage the 
robot can yet sustain. Should this register reach zero, 
your robot explodes, disappearing from the arena. There 
is also a RANDOM register for accessing a random-num- 
ber generator. 



Battle Language 

Programs are written in Battle Language, an assembly- 
like language that supports only simple arithmetic opera- 
tions, the high-level branch constructs IF, GOTO, and 
GOSUB, and the assignment statement TO. Some sur- 
prisingly elegant code is possible with this abbreviated 
set, especially if you use the indexing feature. 

The instruction manual provides examples of basic 
routines needed to control robots. Moving, monitoring 
damage, scanning for enemy robots, and shooting are all 
treated clearly and concisely. The complete source code 
for Mover (see listing 1), a Muse-supplied demonstration 
robot that embodies one of the more sophisticated pre- 
programmed strategies, is also included. 

The best way to learn Battle Language, however, is to 
write a robot program yourself. To facilitate this, Muse 
includes a not-so-rudimentary, screen-oriented text 
editor as one of the main-menu choices. It includes com- 



Number Name 


Type 


1 


A 


Storage 


2 


B 


Storage 


3 


C 


Storage 


4 


D 


Storage 


5 


E 


Storage 


6 


F 


Storage 


7 


G 


Storage 


8 


H 


Storage 


9 


1 


Storage 


10 


J 


Storage 


11 


K 


Storage 


12 


L 


Storage 


13 


M 


Storage 


14 


N 


Storage 


15 


O 


Storage 


16 


P 


Storage 


17 


Q 


Storage 


18 


R 


Storage 


19 


S 


Storage 


20 


T 


Storage 


21 


U 


Storage 


22 


V 


Storage 


23 


w 


Storage 


24 


X 


Current X position 


25 


Y 


Current Y position 


26 


z 


Storage 


27 


AIM 


Control gun aim 


28 


SHOT 


Fires the gun 


29 


RADAR 


Pulse radar 


30 


DAMAGE 


Monitor damage 


31 


SPEEDX 


Control horizontal speed 


32 


SPEEDY 


Control vertical speed 


33 


RANDOM 


Random number generator 


34 


INDEX 


Index to other registers 


Table 1: Registers available to the programmer of a robot's 


computer. 


Twenty-four are 


general-purpose storage regis- 


ters, ten provide control functions of some kind. 



28 December 1981 © BYTE Publications Inc 



Systems Group System 2800 
computers. They're making 
people stand up and take notice. 

But then Systems Group 
products have always appealed 
to those who appreciate sensible 
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That same effort has made 
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Fast, reliable and powerful. 

System 2800 computer sys- 
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Today's Requirements 

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Your Future Requirements 

40M byte hard disk and 20M byte tape 
back-up. single or multi-user system 



plete cursor control and even moving of text "blocks." 
Once the source is complete, it can be assembled and put 
on the "test bench." 

The test bench is a program feature that lets you ex- 
amine the operation of a robot program without actually 
going to the battlefield; it's sort of a dynamic debugger. 
The program statements being executed are displayed on 
the screen along with the values in various registers, and 
instantaneous information on theoretical speed, position, 




Photo 2: The Robotwar battlefield during combat. 



and status of the robot is available. You can single-step 
through the program, stop it altogether, and even 
simulate attacks and radar acquisition of targets. 

To my mind, the test bench is an important idea and 
will probably prove most useful to people just learning to 
program. Although every beginning robot programmer 
(and most veteran ones) will make mistakes when pro- 
gramming a robot, it would be very discouraging for 
most to watch their prize creation blindly beating itself 
against a wall. The test bench gives you the means to find 
bugs — makes it easy, in fact — and to correct them before 
pitting your robot against others. The simplicity of Battle 
Language and the availability of the test bench make pro- 
gramming a less imposing task, especially for beginners, 
and suggest Robotwar's use as an instructional device in 
classroom settings. 

Gird Thy Loins 

When a robot's source code is completed, assembled, 
and the object code is stored on disk, the programmer 
then takes the role of spectator. Robotwar lets you select 
your robot's opponents from a set of adversaries that in- 
cludes robots programmed by Muse as well as those writ- 
ten by your friends or enemies. If you are a solitary 
player, your robot may have no other opponents than 
those the program supplies. Any mix of up to five robots 
and multiples of the same robot are allowed in the arena. 

Preprogrammed robots that come with the game dem- 



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onstrate some simple but increasingly effective strategies 
that can be tough to beat: 

Target does nothing, but still wins once in a while 

because more active robots tend to destroy each other 

first. 

Scanner sits in one spot and scans 360 degrees, looking 

for an enemy; when one is found, Scanner "locks on" and 

keeps firing until the enemy is destroyed. 

Random is similar to Scanner but constantly moves in a 

random pattern. 

Mover is similar to Scanner but, if damaged, moves to a 

new location. 

Bottom remains in constant motion along the south wall 

of the arena, always scans due north, and fires as it passes 

an enemy. 

In a recent ten-game match, Bottom won most often, 
followed by Mover, Random, Target, and Scanner. 

When I first saw Bottom perform, I was perplexed. 
Eventually I realized it was using constant motion to scan 
the whole arena while presenting a moving target to the 
rest of the field. Its evasive action usually allowed it to 
survive the longest. 

Bottom is a rather simplistic program. The robot 
blithely runs a back-and-forth course parallel to the 
arena's south waf but doesn't watch where it's going. 
Should another robot move into its path, the two will 



collide repeatedly until one dies. 

A Small Problem 

The success of Bottom's elegantly simple strategy in- 
spired me to see if a few modifications could fix some of 
its shortcomings and improve its performance. I created 
Tops, a version that mirrored Bottom's wall-hugging mo- 
tion but along the north wall instead. The major dif- 
ference was that Tops would pause to scan its path, and if 
another robot were too close to the north wall, Tops 
would halt and destroy it before continuing. I was 
amazed at the performance: Tops lost every battle I 

It seems there is a more subtle reason for Bottom's 
being programmed to hug the south wall: all the prepro- 
grammed robots, including Bottom, are initialized facing 
north. Tops was a sitting 'droid. Worse yet, it kept run- 
ning into walls and would help destroy itself before it 
traversed the arena five times. The solution to the first 
problem was, of course, to choose a different wall. The 
second problem was more serious and points out a signif- 
icant problem with the game itself: the more sophis- 
ticated a robot's program is, the longer it takes to run and 
the longer a robot takes to react to changing conditions 
(such as an approaching wall). 

A common microcomputer might interpret hundreds 
of thousands of BASIC instructions in one second. 
Robotwar's robots seem to execute fewer than ten in one 
second. Your robot can run into something and inflict 



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32 December 1981 © BYTE Publications Inc 



Circle 302 on inquiry card. 




The guy on the left 
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uy on the left has two file folders, anewsmaga- transmission couplers mean you need never work without 



• I 



The guy on the left has two file folders, a news maga- 
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The guy on the right has the OSBORNE 1 • a fully 
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of a briefcase. Also in the case are the equivalent of over 
1600 typed pages, stored on floppy diskettes. 

The owner of the OSBORNE 1 is going to get more 
work done— and better work done— in less time, and with 
less effort. 

Unfold it, plug it in, and go to work 
like you've never worked before. . . . 

Go to work with WORDSTAR® word processing, so 
your correspondence, reports, and memos take less time 
to produce, and say more of what you wanted to say. And 
with MAILMERGE®— the mailing system that turns out 
personalized mass mailings in the time you'd spend on a 
rough draft. 

Go to work with SUPERCALC®, the electronic 
spreadsheet package that handles complex projections, 
financial planning, statistics, and "what if" questions in- 
stantly. For the more technically minded, SUPERCALC will 
process scientific data and calculate results. 

Go to work with powerful BASIC language tools — 
the CBASIC-2® business BASIC, or the Microsoft BASIC® 
interpreter. 

That's standard equipment. 

Options include about a thousand different software 
packages from a host of vendors designed to run on the 
CP/M® computer system. 
Go to work at the office, at home, or in the field. 

Or anywhere. Optional battery packs and telephone 

Circle 325 on Inquiry card. 



transmission couplers mean you need never work without 
the capabilities of the OSBORNE 1 . That's good, because 
you won't want to work again without it. 
All for $1795. It's inevitable. 

The OSBORNE 1 is the productivity machine that's 
changing the way people work. Put simply, the machine 
delivers a significant productivity edge — day in and day 
out — to virtually anyone who deals with words or num- 
bers. Or both. 

Since the entire system is only $1795, it won't be too 
long before the guy on the left has an OSBORNE 1 of his 
own. The same probably goes for the person reading 
this ad. In fact, we think it's inevitable. 

The OSBORNE 1 includes a Z80A®C 
bytes of RAM memory, two 100 
floppy disk drives, a business keyboard 
built-in monitor, IEEE 488 and RS232 ' 
faces for printers and other things 
get connected to computers, 
CP/M, CBASIC-2, Microsoft BASI 
WORDSTAR, and SUPERCALC. The 
system is available from com' 
puter retailers nationally. 



$1795. It's 
inevitable. 




COMPUTER CORPORATION 

26500 Corporate Avenue Hayward, California 94545 
Phone (415) 887-8080 TWX (910) 383-2021 



BYTE December 1981 



33 



Listing 1: Sample source code for Mover. One of the more so- 
phisticated of the preprogrammed robots, Mover sweeps the 
arena with radar to find an enemy, "locks on" and fires until the 
enemy is destroyed, but is smart enough to take evasive action if 
fired upon. 

250 TO RANDOM ; INITIALIZE RANDOM NUMBER 



START 

DAMAGE TO D 

SCAN 

IF DAMAGE # D GOTO MOVE 
AIM + 17 TO AIM 

SPOT 

AIM TO RADAR 
IF RADAR > GOTO SCAN 
- RADAR TO SHOT 
GOTO SPOT 

MOVE 

RANDOM TO H 
RANDOM TO V 

MOVEX 

H - X * 100 TO SPEEDX 
IF H - X > 10 GOTO MOVEX 
IF H - X < -10 GOTO MOVEX 
TO SPEEDX 

MOVEY 

V - Y * 100 TO SPEEDY 
IF V - Y > 10 GOTO MOVEY 
IF V - Y < -10 GOTO MOVEY 
TO SPEEDY 
GOTO START 



SAVE CURRENT DAMAGE 



TEST : MOVE IF DAMAGED 
IF NOT, INCREMENT AIM 

ALIGN RADAR TO AIM 
SCAN IF NO ENEMY FOUND 
OR SHOOT SPOTTED ENEMY 
IS ENEMY STILL THERE 



;PICK A RANDOM PLACE TO GO 



TRAVEL TO NEW X LOCATION 

TEST X POSITION 

TEST X POSITION 

STOP HORIZONTAL MOVEMENT 



TRAVEL TO NEW Y LOCATION 

TEST Y POSITION 

TEST Y POSITION 

STOP VERTICAL MOVEMENT 

START SCANNING AGAIN 



7Ve 6*Oty quality frvi**4> to- tfa, 

HU&l046*KfMU*t4- utdu4tn.tf 

Now you can have another one of those little extras 

that makes you fee] good about your computer.. 



i!5? s\ 




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on the market, from the people whose only business is the small computer 
user. Our experienced customer staff is ready and waiting to answer 
questions regarding your forms needs. 

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Instruction Meaning 



TO 

+ 



IF 

GOTO 
GOSUB 
ENDSUB 



Stores a value in a register. 

Adds two values. 

Subtracts two values. 

Multiplies two values. 

Divides one value by another. 

Compares two values and alters program sequence. 

Goes to a label in the program. 

Executes a subroutine. 

Returns from a subroutine. 



Table 2: Commands in Battle Language. This simplistic pro- 
gramming language combines high-level branching con- 
structs with low-level access to robot functions. The small 
number of instructions means that beginners don't have to 
master a difficult language just to play the game. 



ypwn (?otnfiiete Siuviu. (a* &HttaKW<6 "pvtmAl 



damage on itself while jumping to a subroutine. Sadly, 
this is going to discourage structured programming in 
favor of straight-line coding (GOSUBs take time). 

Although not of the same magnitude, there is another 
problem that I found vexing: the stalemate. Occasional- 
ly, two robots never detect each other or never score hits 
on one another. Because of timing relationships in the 
game (program lengths, robot speed, and scanning inter- 
vals), robots may continually cycle through the proper 
instructions, performing flawlessly but never damaging 
each other. For instance, Bottom and Scanner might fall 
into a rut where Bottom never "blips" the radar at just the 
right time to see Scanner, while Scanner might see Bot- 
tom but always fires a few degrees off and is never able to 
score a hit. 

Peacetime Use 

Fighting isn't this game's only function. I have tried 
some interesting experiments without firing a shot. My 
favorite involves a robot I call D-Cell (for decelerate). 

D-Cell is programmed to go as far as possible in one 
direction, then turn left a random number of degrees and 
repeat, decelerating or stopping to avoid oncoming ob- 
jects. This is quite a challenge, considering that several 
D-Cells may be roaming around at various speeds on odd 
courses. 

The beauty of Battle Language lies in its simplicity, its 
high-level constructs with low-level access to robot func- 
tions. Unfortunately, Robotwar does not allow the user 
to choose a robot's position or to have it pick up objects. 

Conclusions 

• As a spectator sport, Robotwar is merely interesting. 
People who play it, however, may become obsessed. 

• Battle Language is easy to learn and simple enough to 
allow neophytes to get adequate results in just a few 
minutes. Enough possibilities exist to challenge a veteran 
programmer for hours. 

• Robotwar's text editor and test bench are features that 
demonstrate this product's sophistication. 

• Robotwar is more than just a game. It can be used as an 
educational tool to teach the fundamentals of program- 
ming and process control. ■ 



34 December 1981 © BYTE Publications Inc 



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CRTForm allows you to modify program input specif- 
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COBOL/FORTRAN, PL/ 1, and Ada) to interface the 
programmers' application code to the CRTForm run- 
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• An editor that creates and modifies the specif- 
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A faceless stranger in the crowd presses a slip of paper into your hand and is gone. You are surprised, but only for 
a moment; after all, they had said that you would be contacted. You follow the confusing directions on the paper and 
find yourself somewhere in an unfamiliar part of town. And there it is— the neon sign above the warehouse door 
proclaims "The Coinless Arcade." Something deep inside you knows that it is true. You walk inside, and you see all 
the games you've ever played and a few you never knew existed. Clusters of people, gathered together in friendly 
competition, surround most of the games. You walk up to a vacant machine, one of your favorites, reach into your 
pocket, and pull out a quarter. You start to put it in the machine, but find no slot for it. Smiling, you replace the 
coin in your pocket and press the flashing red button labeled START. The fun begins, and you know it is only the 
beginning. 

Strictly speaking, the Coinless Arcade does not exist. But, in a way, it does: in 
the software available for many of today's microcomputers. We just came back < 
from the Coinless Arcade with photos of some of the newest and best computer 
games around. Take a stroll through our Coinless Arcade. We think you'll like 
what you see. 



iff: 






7/ "Roar!" "Yipel" This is the only 
(| dialogue between the two fighting 
dinosaurs that star in this two-player 
game. The dinosaurs, maneuvered by 
players with joysticks, try to bite each 
other on the back of the neck. A nice 
touch is that the battle is not even to the 
death — when the score of one dinosaur 
goes to zero, it retreats into the dis- 
tance. Dino Wars, by Robert Kilgus, for 



the TRS-80 Color Computer, $39.95 (car- 
tridge), from Radio Shack, One Tandy 
Center, Fort Worth TX 76102. 

The graphics and music of Leo 
Christopherson make Voyage of 
the Valkyrie a top-notch game. You com- 
mand the attack ship Valkyrie and must 
secure the island of Fugloy by finding 
and capturing the ten castles there. 
Norse place names and occasional 



music from Wagner operas lend a 
distinctive style to this game. Voyage of 
the Valkyrie, for the TRS-80 Model I or III 
(shown here) or the Apple II or II Plus, 
$39.95 (disk), from Advanced Operating 
Systems, 450 St. John Road, Suite 792, 
Michigan City IN 46360. 

This original game is, in some 
ways, the opposite of the popular 
Star Castle arcade game. You command 





>enior Editor 





the ship in the middle, and you try to last 
as long as possible against kamikaze 
ships that are battering your shields. 
You can shoot past your shields at the 
enemy ships, but they are very hard to 
hit. Space Warrior, by Marc Goodman, 
lor the Apple II or II Pius, $24.95 (disk), 
from Broderbund Software, 2 Vista Wood 
Way, San Rafael, CA 94901. 



/^dI Apple Panic is one of the most 
'JT creative and novel games to be 
invented for a microcomputer. The small 
creatures after you are "apples," and 
you have only one way of stopping them. 
You must dig holes in the walkway you 
are on; when an "apple" falls into one 
and is temporarily stuck there, you must 
knock it through before it can get out of 
the hole and repair the walkway. Unlike 
so many arcade games that can often 
defeat you in less than a minute, this 
game is slow paced and easy to play (al- 
though It is still challenging). Apple 
Panic, by Ben Serki, for the Apple II or II 
Plus, $29.95 (disk), from Broderbund 
Software, 2 Vista Wood Way, San 
Rafael, CA 94901. 

Kayos is an assault on the 
senses. While a field of asteroids 
distracts your eyes and two colored air- 




craft (middle) try to ram your ship (at 
bottom), your objective is to shoot the 
quickly moving red ship zooming across 
the top of the screen. Kayos, for any 
Atari 400/800, $34.95 (disk or cassette), 
from Computer Magic Ltd, 1 76 Main St, 
Port Washington NY 1 1050. 

/Aj\ The classic game Galactic Empire 
\J has recently been translated for 
the Atari 400 and 800 computers. In this 
free-form game of military strategy, you 
command the flagship Orion and must 
use your limited resources to conquer 
and hold the twenty inhabited planets of 
the known galaxy. Galactic Empire, by 
Douglas Carlston (Atari translation by 
David Simmons), for the Atari 400/800, 
$19.95 (cassette), from Adventure Inter- 
national, POB 3435, Longwood FL 32750. 




.Horn Inc 37 




Jf Olympic Decathlon is the 
il definitive game for the 
armchair athlete. Actually, 
Olympic Decathlon is a series of 
games that lets up to eight 
people compete in the ten 
events of the Decathlon. Timing 
and finger endurance are the 



qualities that guarantee suc- 
cess. In the 110-meter hurdle 
event (shown here), you have to 
press two paddle buttons in an 
exact sequence to make your 
player "run"; he jumps when 
you hold down a button for 
longer than an instant. Olympic 



Decathlon, by Timothy Smith, for 
the Apple II or II Plus, $29.95 
(disk), or the Radio Shack 
TRS-80, $29.95 (disk or 
cassette), from Microsoft 
Consumer Products, 400 18th 
Ave NE, Suite 200, Bellevue WA 
98004. 




Earth is a battleground! 

You must patrol the skies, 
shoot down strange creatures 
that materialize from thin air, 
and rescue humans that are 
being abducted by a mysterious 
blue-winged creature. This 
game, loosely based on the 
Williams Defender coin-operated 
game, has the most breath- 
taking graphics I've seen to 
date! Gorgon, by Nasir Gebelli, 
for the Apple II or II Plus, $39.95 
(disk), from Sirius Software, 
2011 Arden Way #225A, 
Sacramento CA 95825. 





Most microcomputer 
games that are versions of 
existing board or equipment 
games aren't worth the disks 
they're printed on, but Raster 
Blaster does not fall into that 
category! Ignore the totally 
realistic ball movement if you 
want to, but the robot arms that 
can hold a ball in play for later 
release are a feature that no 






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existing pinball machine can 
match. Raster Blaster, by Bill 
Budge, for the Apple II or II 
Plus, $29.95 (disk), from 
BudgeCo, 428 Pala Avenue, 
Piedmont CA 94611. 

Ml Missile Command, one of 
TT the most popular coin- 
operated arcade games to date, 
is now available in a cartridge 
for the Atari 400 or 800 
computers. The trackball of the 
coin-operated version has been 
replaced by an Atari joystick, 
and you have only one missile 
base (not three), but the sights, 
sounds, and behavior of the 
original game are still there. 
Missile Command, for the Atari 
400/800 computer, $39.95 (car- 
tridge), from Atari Inc. Consumer 
Division, 1195 Borregas Ave, 
Sunnyvale CA 94086. 

This night-driving game 
features five Grand Prix- 
type racetracks, manual or 
automatic conditions, sound, 
varying road conditions, and 
several other options. The 
graphics and human engineering 
on this game are very good. 
International Grand Prix, by 
Richard Orban, for the Apple II 
or II Plus, $30.00 (disk), from 
Riverbank Software Inc, POB 
128, Smith's Landing Road, 
Denton MD 21629. 




/So you like the Pac-Man 
arcade game? Then your 
only decision is which 
microcomputer look-alike to 
buy — Snoggle (left) or Gobbler 
(right). Snoggle reproduces the 
play of the original game better, 
but Gobbler has smoother and 
more interesting graphics. Both 



are for the Apple II. Snoggle, by 
Jun Wada and Ken Iba, $32.95 
(disk), from Broderbund Soft- 
ware, Box 3266, Eugene OR 
97403. Gobbler, by Olaf 
Lubecke, $24.95 (disk), from 
On-Line Systems, 36575 Mudge 
Ranch Road, Coarsegold CA 
93614. 




Computer-game enthusi- 
asts have been "landing" 
spaceships on other planets for 
as long as computers have been 
around. Now you can try your 
skill on the Commodore VIC with 
the new Super Lander game. Of 
course, the most dangerous 
landing sites are the most 
rewarding. VIC Super Lander, for 
the Commodore VIC computer, 
$29.95 (cartridge), from 
Commodore Business Machines, 
681 Moore Rd, King of Prussia, 
PA 19406. 




Most arcade games give 
you three "lives." When 
you use them up, the games 
end. Not so with Star Thief; 
destroyed ships are recreated at 
the edge of the screen, and you 
keep playing until various enemy 
ships carry off all the "power- 
pods" in the center of the 
screen. The game, based 
loosely on the Ripoff coin- 
operated arcade game, can be 
played from either the keyboard 
or the game paddles and has a 
two-player cooperative 
version — both of you against the 
computer. Star Thief, by James 
Nitchals, for the Apple II or II 
Plus, $29.95 (disk), from Cavalier 
Computer, POB 2032, Del Mar 
CA 92014. 



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/^ Eastern From (7947) /'s 
T/* possibly the first fun war 
game for people who hate war 
games. The playing screen is 
several times larger than the 
video-display window — but you 
can see the entire map by 
smoothly scrolling the window 
across it! Also, the map 
changes with the seasons, the 
game has no charts or tables 
(the computer does all the 
calculations automatically), and 



there are no long waits for the 
computer to finish a move (it 
does its calculations while you 
are entering your moves). 
Eastern Front (1941), by Chris 
Crawford, for the Atari 400 or 
800 computers, $26.95 
(cassette) or $29.95 (disk) plus 
$2.50 shipping and handling, 
from the Atari Program 
Exchange, POB 427, 155 Moffett 
Park Dr, Sunnyvale CA 94086. 




"From darkest dungeons to 
deepest space!" This 
extravagant claim is fulfilled by 
the game Ultima, a graphics- 
oriented role-playing game. The 
game takes place in several 
locations — outdoors (shown 
here) and in space, a three- 
dimensional dungeon, and a 
castle. Ultima, by Lord British, 
for the Apple II or II Plus, $39.95 
(disk), from California Pacific 
Computer Co, 1623 Fifth St, 
Davis CA 95616. 

JjL Even though you're in the 
nSt Asylum, they are trying to 
kill you, and you have until 
morning to get out! Asylum is an 
adventure game (that is, a 
puzzle to be solved) with 
graphics, full-sentence 
commands, and a real-time 
clock that gives you a deadline 
for getting out. Not only is it a 
devious game, it is a very good 
buy for the money. Asylum, by 
Frank Corr, Jr and William 
Denman, Jr, for the Radio Shack 
TRS-80 Models I and III, $14.95 
(cassette), $19.95 (disk), from 
Med Systems Software, POB 
2674, Chapel Hill NC 27514. 



Ciarcia's Circuit Cellar 



Build a Touch Tone 
Decoder for Remote Control 



Steve Ciarcia 

POB 582 

Glastonbury CT 06033 



I'm lucky. Every month I can chip 
away at my mental list of unfulfilled 
fantasies through my Circuit Cellar 
project for BYTE. The editorial staff 
thinks of these articles as "a selected 
mixture of electronic theory and 
hardware presented as a practical ap- 
plication for personal-computing en- 
thusiasts." [That's what Steve thinks 
we think. . . .RSS] Up to now I have 
carefully avoided revealing my true 
motivations. 

This month, however, my "selected 
mixture" turned into a long-term 
engineering project. Let me explain. 

I have always wanted to be able to 
telephone the computerized home- 
control system in my house from 
anywhere in the country, to find out 
what the conditions are like in and 
around the house, be informed of 
problems or messages, and remotely 
control lights and thermostat settings. 

This idea is neither new nor 
something found only in science fic- 
tion. Any computer presently 
equipped with an autoanswer modem 
could conduct such a dialogue with a 
remote user terminal, transmitting 
and receiving ASCII (American Stan- 



Touch Tone is a registered trademark of the 
Bell System for its dual-tone, multiple-frequency 
signaling system. 

Some figures accompanying this article were 
provided through the courtesy of the Interna- 
tional Telephone & Telegraph Corporation and 
Mostek Corporation. 



dard Code for Information Inter- 
change) characters. 

But I really don't want to carry an 
ASCII terminal with me. For the sim- 
ple functions I propose, even carrying 
a small pocket terminal is quite a 
bother. I don't need a full keyboard 
for a few simple coded inputs, and 
with a little innovative thinking I can 
eliminate the need for a message 
display at the remote end of the com- 
munication. 

Innovative Thinking 

The keypad on a Touch Tone 
telephone receiver is a readily 
available, convenient means of 
transmitting data. (Only telephone 
instruments from the Bell System are 
properly called Touch Tone; the 
generic term used by other telephone 
manufacturers is dual-tone, multiple- 
frequency, or DTMF, signaling.) 
Where only rotary-dial telephones 
are available, a battery-powered 
DTMF keypad can be carried much 
more easily than any full-function 
terminal. Decoding of DTMF signals 
by my home-control computer, 
therefore, became one cornerstone of 
my remote-command arrangement. 

The other cornerstone was to be 
output in the form of audible 
responses: words spoken over the 
telephone line by a voice synthesizer 
driven by the computer. Those who 
have read my June and September 
1981 articles know I have been ex- 
perimenting with two voice-synthesis 



integrated circuits: the Digi talker 
from National Semiconductor and 
the Votrax SC-01 from the Votrax 
Division of Federal Screw Works. Us- 
ing these components, I designed the 
Micromouth and Sweet Talker speech 
interfaces, respectively. Either of 
these, interfaced in an approved way 
to the telephone line, could give me 
the voice-response capability I envi- 
sioned. 

My first step was to decode the 
DTMF tones. As the title of this arti- 
cle indicates, I didn't get much fur- 
ther. 

Pitfalls for the Unwary 

There are many decoding schemes. 
Most work only at room temperature 
when the tide is high and the moon is 
full. Even though they might work 
under ideal circumstances, the cir- 
cumstances encountered in transcon- 
tinental communication are often far 
from ideal. Decoding DTMF tones 
reliably turned out to be a much more 
difficult task than I imagined. 

Budgeting a couple of days to build 
the DTMF decoder and set up the 
telephone interface, I started by look- 
ing through other magazines for ap- 
propriate circuits. There were very 
few such circuits (this should have 
been a clue), and most of them used 
type-567 small-scale-integration 
phase-locked-loop tone-decoder 
chips. 

In a classic me-too approach, I 
wired up seven LM567 tone decoders 



42 December 1981 © BYTE Publications Inc 



and tested a quick-and-dirty circuit. 
Unsatisfied with its reliability, I add- 
ed a separate bandpass filter to the in- 
put of each LM567. This greatly im- 
proved the signal-to-noise ratio, but 
it used a hundred components. I put 
this circuit aside and tried using 
separate bandpass filters with an in- 
tegrated DTMF tone-decoder chip. 
This reduced the component count by 
25 percent, but it was hardly the 
"quick-build" Circuit Cellar project I 
wanted. I soon realized why I hadn't 
seen many articles on personal ap- 
plications of DTMF decoding. 

Telephoning my computer and 
having it respond with audible words 
will have to wait. We have to begin 
with the subtopic of DTMF encoding 
and decoding. 

Principles of DTMF 

The next time you pick up the 
handset of a Touch Tone or other 
DTMF-dialing telephone receiver, 
press one of the keys and listen. The 
sound you hear, aside from the dial 
tone, is not a single-frequency sine 
wave but a combination of two fre- 
quencies. The 12 keys are arranged in 
four rows and three columns, as 
shown in table 1 on page 45. All the 
keys in a given row or column have 
one tone in common. For example, 
pressing the digit "9" (row 3 and col- 
umn 3) produces an 852 Hz and a 
1477 Hz tone simultaneously. 
Similarly, pressing "4" (row 2 and 
column 1) produces 770 Hz and 1209 
Hz tones simultaneously. 

The full DTMF-encoding standard 
defines four rows and four columns 
for a total of 16 two-tone combina- 
tions. Standard telephones use only 
12 of these combinations, but for the 
purposes of this discussion we shall 
consider all 16. Depending upon your 
application, these extra codes may be 
useful. 

The eight frequencies associated 
with the rows and columns are 
separated into two groups. The low 
group, containing row information, 
has a range of 697 Hz to 941 Hz. The 
high group, containing column infor- 
mation, covers 1209 Hz to 1633 Hz. 

Copyright © 1981 by Steven A. Ciarcia. 
All rights reserved. 




Photo la: A standard Touch Tone DTMF-encoding module used by the Bell 
System. It can encode tone pairs for four rows and three columns of the full 
DTMF matrix. 




Photo lb: The back side of the Touch Tone module showing the transistorized in- 
ductance/capacitance oscillators and the mechanical levers and contacts. 



December 1981 © BYTE Publications Inc 43 



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3 




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14 


B r 












T [ 


1 




1 




1 




1 






4 




5 




6 




B 


13 


< "load 












1 




1 




1 




1 




/h 


7 




8 




9 




C 


12 














1 




1 




1 




1 




















11 































4-BY-4 MATRIX KEYPAD 



I 



j-^ DTMF 

"— ^ TONE OUTPUT 



Figure lb: Schematic diagram of a DTMF-encoding circuit that employs the MK.5087, a 4-by-4 matrix keypad, and a 3.579545 MHz 
color-burst crystal. 



44 December 1981 © BYTE Publications Inc 



As you can see from table 1, there is 
little bandwidth between frequencies. 

A variety of methods are employed 
to generate and decode these tone 
combinations. Generally, the level of 
sophistication employed in these cir- 
cuits is governed by the application. 
Telephone companies strive for 
reliability and aren't particularly con- 
cerned with the size and weight of the 
result. Apparently, the telephone- 
company engineers' primary concern 
is that the system should still work 20 
years from now and withstand a 
nuclear attack. Thus, except in the 
very latest equipment, discrete LC- 
(inductance/capacitance) tuned cir- 
cuits are usually found in telephone- 
company equipment. 

Non-telephone-company commer- 
cial users of DTMF signaling take a 
different approach. Instead of LC- 
tuned circuits, they generally prefer 
crystal-controlled integrated-circui t- 
based systems. One system is not 
necessarily better than the other, but 
the large telephone companies have 
more facilities for winding inductors. 

In computer-control applications, 
the approach I recommend is to 
follow in the footsteps of the com- 
mercial designers, using large-scale- 
integrated circuits where possible. In 
the case of encoding the row and col- 
umn signals, this route is obvious and 
the cost is relatively low. DTMF 
decoding, on the other hand, is fairly 
complicated and relatively expensive. 
Before choosing one of the cheaper 
approaches, try to make a fair 
evaluation of the time involved in 
building and troubleshooting such a 
circuit and weigh that against a slight- 
ly more expensive integrated circuit 
with fewer potential problems. 

DTMF Encoding 

Telephone companies have tradi- 
tionally used transistor LC oscillators 
to encode the DTMF tone pairs. The 
practical alternative for the rest of us 
is use of an integrated tone-encoder 
component, such as the MM53125 
from National Semiconductor and 
the MK5087 from Mostek. Referred 
to as integrated tone-dialer circuits, 
these chips divide a 3.579545 MHz 
reference frequency into the eight 
DTMF frequencies. The frequency 



combinations are selected by a 12- or 
16-key matrix keypad connected 
directly to the chip. The output is a 
stair-step D/A (digital-to-analog) ap- 
proximation of the mixture of the 
high- and low-group tones. No fre- 
quency adjustment is necessary to 
meet standard DTMF specifications, 
and the average circuit configuration 
requires little more than the keypad, 
a crystal, and the integrated circuit. 
Figure 1 shows a block diagram of the 



MK5087 and a typical DTMF- 
encoder circuit. 

If you don't want to assemble a 
DTMF encoder, Radio Shack sells an 
encoder complete with a 12-key 
keypad. Using an MM53125, the 
CEX-4000 tone-generating keypad 
module (catalog number 277-1010) 
presently costs $16.95. To use it, you 
also need a 3.579545 MHz crystal 
(number 272-1310), which costs 
$1.99. Simply add a power supply 




Photo 2: The Radio Shack DTMF-encoding keypad module (catalog number 
277-1010), which incorporates the National Semiconductor MM53125 tone- 
encoder chip. 



High Group 



Column Column 1 Column 2 Column 3 
1209 Hz 1336 Hz 1477 Hz 1633 Hz 



Low 
Group 



Row 0, 697 Hz 
Row 1 , 770 Hz 
Row 2, 852 Hz 
Row 3, 941 Hz 



© 

© 


O 



© 
© 
© 

© 



© 
© 



© 



© 
© 
© 
© 



Table 1: The dialing matrix of the DTMF (dual-tone, multiple-frequency) signaling 
system. The two-dimensional matrix allows 16 different combinations of tones to 
represent 10 digits and 6 control signals. The low-group frequencies correspond to 
the matrix row; the high-group frequencies correspond to the column. Column 3 is 
not normally used in tone dialing, but it can be useful in remote-control applications. 



December 1981 © BYTE Publications Inc 45 



Number 


Type 


+ 5 V 


GND 


-12 V 


+ 12 V 


IC1 


MC1458 






4 


8 


IC2 


MC1458 






4 


8 


IC3 


MC1458 






4 


8 


IC4 


MC1458 






4 


8 


IC5 


LM567 


4 


7 






IC6 


LM567 


4 


7 






IC7 


LM567 


4 


7 






IC8 


LM567 


4 


7 






IC9 


LM567 


4 


7 






IC10 


LM567 


4 


7 






IC11 


LM567 


4 


7 






IC12 


74LS02 


14 


7 






IC13 


74LS02 


14 


7 






IC14 


74LS02 


14 


7 







ANALOG INPUT 




/VOrf.- ADJUST TRIM POT 
ON EACH FILTER 
TO PEAK AT 
TONE-DECODER 
SET POINT. 



and speaker to make it fully opera- 
tional. 

DTMF Decoding 

DTMF decoding is considerably 
more complicated than DTMF en- 
coding. Only recently has the advent 
of the single-chip decoder/receiver, 
such as the ITT MSD3210, made 
reliable DTMF decoding easy to 
achieve. In fact, I didn't find out 
about this hybrid component until 



after attempting to build a number of 
other circuits. If I had had this device 
initially, I could have devoted more 
time to the other parts of my remote 
home-control arrangement. How- 
ever, since you might appreciate the 
MSD3210 and its kin more by seeing 
what you are missing, I will cover 
some of the other circuits I con- 
structed. 

The circuits range in complexity 
from approximately 100 components 



down to just two: a single integrated 
circuit and a crystal. 

Discrete-Filter DTMF Decoder 

Whatever the circuit, the purpose 
of a DTMF receiver is to decode tones 
that indicate which key was pressed 
on the transmitter. The output from 
the decoder can be a logic pulse on 
one of 12 output lines, a 4-bit binary 
code, or separate 2-bit row and 2-bit 
column outputs. The latter two 



46 December 1981 © BYTE Publications Inc 



IC5 LM567 
IN 697 Hz OUT 



TR TC OF LF 



|5 * ( 

I Wv— II 

14. 3K 



lO.ljiF 



:2-2^F 



+ 5V 

|20K 
8 1 



2 4.7K 
i ^AA<- 



il.O/iF 



ffi 



IC6 LM567 
IN 852 Hz OUT 



TR TC OF LF 

~F~* P F F 

^"^ * -kit/** 



11.74K 



lO.ljiF 



+ 5V 

J20K 
8 1 



4.7K 



:i.o m f 



m 



IC7 LM567 
IN 1209 Hz OUT 



TR TC OF LF 




JO.l/iF 



;2.2^F lh 



+ 5V 
220K 



4.7K 



:i.o^f 



IC8 LM567 
IN 1477 Hz OUT 



TR TC OF LF 



' — v\* — ii —•—•>•>. .c 1 * 



6.81K 



;o.i/iF 



;2.2/iF 



+ 5V 
|20K 



2 4.7K 



;i.o^f 



IC9 LM567 
IN 770 Hz OUT 



TR TC OF LF 




15 , I ■ 

— Wr- 

13. OK 



J—O.lHf 



;2.2/iF 



+ 5V 
>20K 



4.7K 



;i.0/iF 



IC10 LM567 
IN 9*1 Hz 0UT 



TR TC OF LF 




|5 * |6 

— wv— 

10. 7K 



IO.l/iF 



;2.2^F 



+ 5V 

: 20K 
8 



2 4.7K 



il.O^F 



IC11 LM567 
IN 1336 Hz OUT 

TR TC OF LF 




J^O.l/xF 



;2.2^F 



+ 5V 

!20K 



4.7K 



;i.0/iF 



220/lF 



*1% RESISTORS 



fff 



Ji^^-H 



OUTPUT 
DIGIT 

■O 1 



jjrir^o*— o 



ici2 

74LS02 



^>^ 



-03 



^jisT^o 4 — o 



^jZ^-i 



-04 



JuT^-H 



-Ob 



IC13 
74LS02 



J^>12_c> 



^J^Tyi-o 



;^^>i-o 



J*^c4-h 



-0° 



IC14 
74LS02 



^>r^-C> 



\~^y^ 



-o* 



Figure 2: Schematic diagram of a DTMF-decoding circuit that employs separate LM567 tone decoders with associated input filters for 
a total of approximately 100 components. 



December 1981 © BYTE Publications Inc 47 



methods combined with a "tone- 
detect" strobe signal are most fre- 
quently employed for connecting the 
DTMF receiver to a computer. 

Most of the DTMF receiver circuits 
produced by hobbyists have incor- 



porated seven type-567 tone-detector 
chips, one for each of the four low- 
group frequencies and for three of the 
four high-group frequencies (the 
fourth high-group frequency is not 
needed in many applications). The 




Photo 3: A Touch Tone DTMF receiver, used by the Bell System, consisting of 
tuned inductance/ capacitance circuits and relays. This type of transistorized 
analog tone detector is quite accurate but very bulky. 




Photo 4: The assembled prototype of the DTMF-decoding circuit shown in the 
schematic diagram of figure 2. This brute-force method requires about 100 com- 
ponents that take much patience to assemble and adjust. 



LM567 is a phase-locked-loop fre- 
quency detector that can be adjusted 
to detect the presence of a particular 
frequency even at very low signal-to- 
noise ratios. Detection errors are 
reduced with the addition of high- 
gain bandpass filters on each LM567 
input. 

The usual technique is to connect 
the seven or eight LM567 analog fre- 
quency detectors in parallel. With 
one LM567 adjusted to each of the 
frequencies in table 1, DTMF 
decoding simply consists of determin- 
ing which pair of LM567s is detecting 
tones. While this circuit works fine in 
the lab (or Circuit Cellar) under ideal 
conditions, experience has shown 
that the extraneous noise often pres- 
ent on telephone lines can cause con- 
siderable false detection. 

Figure 2 illustrates a slightly better 
12-key analog DTMF receiver that 
uses separate filters and LM567 tone 
decoders. Each filter and tone 
decoder combination is tuned for a 
specific frequency. Three 74LS02 
quad two-input NOR gates, IC12 
through IC14, present a l-of-12-line 
output. Stable operation of this cir- 
cuit requires the use of Mylar or 
polycarbonate capacitors in each 
filter section and 1-percent-precision 
resistors where noted. 

Integrated Tone-Receiver Chips 

The alternative approach to analog 
DTMF decoding is digital. The first 
DTMF receiver I built that I trusted 
used a CMOS (complementary metal- 





Lower 


Upper 




Detection 


Detection 


DTMF 


Frequency Frequency 


Frequency (Hz) 


Limit (Hz) 


Limit (Hz) 


697 


683 


711 


770 


755 


786 


852 


834 


869 


941 


922 


960 


1209 


1184 


1233 


1336 


1309 


1363 


1477 


1447 


1507 


1'633 


1600 


1666 


Table 2: The standard DTMF frequen- 


cies with the minimum and maximum 


values accepted within the 2-percent 


tolerance of 


digital tone-decoding 


devices such as 


the Mostek MK5102. 



48 December 1981 © BYTE Publications Inc 



Circle 363 on inquiry card. 



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Circle 126 on inquiry card. 




CP/M is a registered trademark of Digital Research. MP/M II, 
LINK-80, RMAC, LIB-80, and RDT are trademarks ol Digital Research, 
" Copyright 1981 Digital Research 



ID DJGITflL RESEARCH* 



(3al 



HIGH GROUP O- 



r 



AMPLIFIER 



PERIOD 
COUNTER 
AND 
AVERAGER 



OSC IN rz>- 

OSC OUT <^> 



3.579545 MHz 

OSCILLATOR 

CIRCUITRY 



DIVIDER 



LOW GROUP O 



AMPLIFIER 



SYSTEM CLOCK 



PERIOD 
COUNTER 
AND 
AVERAGER 



v+ O- 



COINCIDENCE TIMER 
INTERDIGIT TIMER 



I 



CONTROL LOGIC AND 
CODE CONVERTER 



h 



1 







FORMAT 
CONTROL 



4 BIT 
OUTPUT 



STROBE 



H 



Figure 3a: Block diagram of the Mostek MK5102 DTMF decoder/ receiver. This device accepts DTMF signal inputs in two frequency 
bands, one each for the high group and low group of tones. A digital method is used to count the frequency of the signal being 
received. 



oxide semiconductor) integrated 
tone-receiver chip, the Mostek 
MK5102. The internal functions of 
this device are shown in figure 3a on 
page 52; its input-filter requirements 
are shown in figure 3b. Figure 3c 
shows a block diagram of a typical 



DTMF-receiver circuit using the 
MK5102. It consists of three basic 
components: group filters, limiters, 
and digital tone receiver. 

In a digital DTMF-receiver circuit, 
the input is first separated through 
filters into the low-group frequencies 



(3b) 



697 Hi 941 Hz 1209 Hz 1633 Hz 



OdB 


r 












-5dB 






/l 
/l 








-lOdB 






1 
1 








-15dB 


J 




1 
1 
j 








-20dB 
-25dB 


/ LOW- 
/ GROUP 
/ FILTER 




1 

1 

1 

\ 1 
1 1 


HIGH- 
GROUP 
FILTER 






-30dB 

-33dB 


■■■/... 




\l 

v 


i i i 


i 


^ ' 


soo 


1000 






2000 


3000 






FREQUENCY 


(H 


) 







RELATIVE INPUT LEVEL VI FREQUENCY 

Figure 3b: Input frequency-band requirements of the MK5102. As you can see, the 
required bandpass slopes are stringently steep. 



and the high-group frequencies. The 
amplitude is then hard-limited to 
match the tone receiver's input cir- 
cuitry. The MK5102 detects the 
DTMF tone through a digital count- 
ing method. The zero crossings of the 
incoming waveforms are counted for 
nine periods and the results averaged 
over a longer period. (For these 
counting-type integrated tone 
receivers to operate correctly, the in- 
put frequency must be exact within 
±2 percent, as shown in table 2.) 
When a valid DTMF-digit tone pair 
has persisted for a minimum of 33 
milliseconds, the data are latched on- 
to the outputs, and the output strobe 
goes high. When the valid digit is no 
longer received, the output strobe 
goes low. 

Many experimenters have been led 
down the garden path with regard to 
these integrated tone-receiver chips. 
At $20 they appear to be a bargain. 
But the difficult part of implementing 
this circuit is not decoding the tone 
pairs; the filters cause the problem. 



52 December 1981 © BYTE Publications Inc 



(3c) 



OTMF 

ANALOG 

INPUT 



HIGH-GROUP 
FILTER 



LIMITER 



LOW-GROUP 
FILTER 



LIMITER 



HG IN 



LG IN 




INTEGRATED 

TONE-RECEIVER 

CHIP 



Figure 3c: Block diagram of a typical DTMF- receiver circuit that uses an in- 
tegrated tone receiver like the MK5102 with high- and low-group filters and 
limiters. 



2-OF-8 OR 
) BINARY-CODED 
OUTPUT 



STROBE 



HIH 

3.579545 MHi CRYSTAL 



As you can see in figure 3b, the 
bandpass requirements are excep- 
tionally tight. Many people buy the 
tone-receiver chip only to realize they 
can't design filters. 

Dusting off my disused filter-design 
talents, I decided to see if this method 
was feasible at all. Figure 4 on page 54 
shows an outline of the bandpass- 
filter method I used. It consists of a 
fifth-order high-pass filter in series 
with a fifth-order low-pass filter. The 
circuit was duplicated and tuned 
separately to cover each of the two 
group ranges. 

On the high-group side, for exam- 
ple, the high -pass section allows all 
frequencies above 1150 Hz to pass 
through. The output of this section in 
turn is fed to a low-pass filter with a 
cutoff beginning at 1650 Hz. 
Theoretically, the combined circuit 
should be a bandpass filter that passes 
only the frequencies between 1150 Hz 
and 1650 Hz. Similarly, on the low- 
group side, the bandpass was selected 
to be the range of 650 Hz to 1000 Hz. 
Figure 5 on pages 56 and 57 is a 
schematic diagram of a circuit that 
embodies the design in the block 
diagram of figure 4. 

Wiring and testing this circuit gave 
me a much greater appreciation for 
LSI (large-scale integration) devices. 
While the circuit of figure 5 does 
work, the filters have a cutoff slope of 
only 30 dB per octave, which is 
marginal. The MK5102 generally re- 
quires a band separation of 33 dB, but 



it will receive correctly with separa- 
tion as poor as 22 dB if there is no 
noise. Everything worked under Cir- 
cuit Cellar conditions, but I won't 
guarantee anything on the telephone 
line without further experimentation. 
A definite improvement could be 
obtained by using faster operational 
amplifiers, such as LM318s, instead 
of the LM741s and MC1458s used 
here. However, I merely wanted to 
see if building such a circuit was feasi- 
ble, and I don't necessarily recom- 



mend its use, especially considering 
the DTMF receivers I am about to 
describe. 

Hybrid Bandpass Filters 

The answer to the previous prob- 
lem is to buy an off-the-shelf filter 
with the exact requirements necessary 
for DTMF decoding. Of particular 
significance is a pair of hybrid band- 
pass filters from ITT (International 
Telephone & Telegraph Corporation) 
North, Microsystems Division, called 
Text continued on page 58 




Photo 5: Prototype of the DTMF-decoding circuit of figure 7. This much more 
compact approach to DTMF decoding uses two ITT 8-pole hybrid bandpass 
filters (for group separation) and the Mostek MK5102 DTMF decoder/ receiver. 
The total cost of the parts is about $85. 



December 1981 © BYTE Publications Inc 53 



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54 December 1981 © BYTE Publications Inc 



Circle 426 on inquiry card. 



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The Soft .« =— 
Video 
Switch is 
an auto- 
matic ver- 
sion of the 
popular 
Switch- 
plate. It 
knows 

whether it should display 40 or 80 
columns or Apple graphics. It does 
the tedious work of switching video- 
out signals so you don't have to. The 
Soft Video Switch can be controlled 
by software. Any Videoterm with 
Firmware 2.0 or greater may be 
used with the Soft Video Switch. 
The single wire shift mod is also sup- 
ported. Package price is $35.00. 




■ KEYBOARD AND 
DISPLAY ENHANCER 




The original Keyboard and Display 
Enhancer is still available for Revi- 
sion 0-6 Apples (on which the new 
Enhancer ][ will not fit). These 
Apples have memory select sockets 
at chip locations D1. E1 S. F1. The 
Keyboard and Display Enhancer 
allows entry and display of upper & 
lower case letters with fully func- 
tional shift keys. It does NOT have 
user definable keys nor a type ahead 
buffer. The price is $129.00. 



■ ACCESSORIES: 

Videoterm Utilities Disc $37.00 
[includes) 

• Font Editor 

• Pascal Mid-Res Graphics 

• Applesoft Read Screen Utility 

• Top S. Bottom Scrolling 

• Pascal Vidpatch 

• Graphics Template 
Character Set EPROMs $29.00 ea 

• Half Intensity 

• Inverse 

• German 

• Katakana (Japanese) 

• Line Drawing Graphics 
(Expanded) 

• Spanish 

• French 

• Math & Greek Symbols 

• Super & Subscript 
Dvorak EPROM 

(Enhancer) $29.00 

Lower Case Chip $29.00 



HIGH-PASS FILTER 



DTMF 0- 1 / lF 

ANALOG 
INPUT 



1N914 

-W- 



1N914 

-w- 



100K 





CI 

LM741 



NOTE: ALL CAPACITORS ARE 

MYLAR OR POLYCARBONATE 



HIGH-PASS FILTER 




Figure 5: .4 /i/fer ci'rcwif few'/f from separate high-pass and low-pass stages for the high and low tone groups. While this circuit can be 
used with the MK5102, hybrid bandpass filters such as the ITT 3044 and 3045 exhibit superior performance. 




G3 G3 C3 G3 1 

G3G3GE 

C3l 




New! Tl LCD Programmer. 

Hexadecimal and Octal Calculator/Converter. 

The brand new tilt-top Tl LCD Programmer can save you 
hours of work. It was designed specifically for the 
problems you do, and has features that make it ideally 
suited for applications in computer programming, 
debugging, repair and digital logic design. 

• Performs arithmetic in any of three number bases — OCT, 
DEC, HEX. 

• Integer, two's complement arithmetic in OCT and HEX. 

• One's complement capability in OCT and HEX. 

• Converts numbers between OCT, DEC and HEX. 

• Fifteen sets of parentheses available at each of four 
processing levels. 

• Logical functions AND, OR, EXCLUSIVE OR and SHIFT 
operate bit by bit on OCT or HEX numbers. 

Unisource Electronics has committed to buy Tl's initial 
production of this unique product. Availability is 
limited! Order now. 



15-Day Free Trial. 

The best way to evaluate the Tl LCD 
Programmer is to try it yourself — on the 
job — for 15 days. If you're not 100% 
satisfied, simply return it for a full refund. 
Order now by calling toll-free: 

1-800-858-4580 

In Texas call 1-806-745-8835 
Lines open 8 am to 6 pm CST 

Just give us your name, shipping address 
and Visa or MasterCard number and we 
will charge the tax deductible' $75.00 
purchase price, plus $2.00 shipping and 
handling (Texas residents also add 5% 
sales tax) to your account. Or send your 
check or money orde* la*. 

Unisource Electronics, Inc. 

P.O. Box 64240 • Lubbock, Tx. 79464 
" When used for business. 



56 December 1981 © BYTE Publications Inc 



Circle 460 on inquiry card. 



LOW -PASS FILTER 




•39K 



56K 
-WV- 



10K 10K 5 
i >-WV f Wl — f 




;0.012/iF 



m 



0.012/xF 



LI MITER 

1N914 

— w— 



1N914 

H4- 



100K 
— VW— 




■o 



HIGH-GROUP 
OUTPUT 



NOTE: ALL CAPACITORS ARE 

MYLAR OR POLYCARBONATE 



LOW-PASS FILTER 




10K 




LI MITER 

1N914 

— w— 



1N914 

H4- 



100K 
-Vrt- 




LOW-GROUP 
OUTPUT 



Number 


Type 


-12 V 


+ 12 V 


IC1 


LM741 


4 


7 


IC2 


MC1458 


4 


8 


IC3 


MC1458 


4 


8 


IC4 


MC1458 


4 


8 


IC5 


LM741 


4 


7 


IC6 


LM741 


4 


7 


IC7 


MC1458 


4 


8 


IC8 


MC1458 


4 


8 


IC9 


MC1458 


4 


8 



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m 






Circle 175 on inquiry card. 



December 1981 © BYTE Publications Inc 57 



Circle 134 on inquiry card. 



68000 p? on 
the S-100 Bus? 



YES, AVAILABLE NOW 
FROM DUAL SYSTEMS! 

D 8 mHz 68000 microprocessor. 

□ 16-megabyte direct addressing. 
D 32-bit internal arithmetic. 

D Minicomputer type instructions 

including MULTIPLY. 

□ FULL IEEE-696 S-100 compliance. 

Runs with all 4 mHz S-100 boards 
and automatically runs faster 
when accessing Dual Systems 
memory boards, for FULL SPEED 
OPERATION OF THE 68000. 

D Powerful vectored interrupts. 

7 Vectored interrupts, including 
NMI, as well as alternate mode 
having up to 256 interrupts. 

□ On board monitor ROM for 

immediate use. 

D Connector for future addition 
of memory management unit for 
multi-user operating systems. 

D Built to the highest industrial 
standards with 200 hour burn-in. 




CPU/68000 CPU board $1195 

32K-byte 8/16-bit NONVOLATILE 
RAM board, for secure storage of 
programs you are developing. 
Allows FULL SPEED CPU operation. 
CMEM-32K, per 32K-bytes . . $895 

32K-byte 8/16-bit EPROM board, 
EPROM-32K $245 

Serial I/O board, SIO-2 $285 

All of the above with cabinet, power 
supply and backplane $3685 

OEM and Dealer pricing is available. 

Sales representatives in most metropolitan areas. 




system reliability/system integrity 

DUAL SYSTEMS 
CONTROL CORPORATION 

720 Channing Way, Berkeley, CA 94710 
(415)549-3854 • TWX 910 366-2035 



Text continued from page 53: 
the 3044/3045 DTMF group filters. 
Each filter is contained in a 24-pin 
dual-inline package and plugs into a 
standard integrated-circuit socket. In- 
ternally, each is an 8-pole bandpass 
filter with specifications far exceeding 
the minimum requirements of the 
MK5102. (A performance curve of 
the model 3044/3045 filters is shown 
in figure 6 on page 58.) 



Or 
-10 
-20 
-30 
-40 
-50 
-60 



-80 



Using these filters, the entire DTMF 
receiver can be constructed with only 
16 components, as shown in figure 7 
on page 62, a vast improvement over 
the complex circuits of figures 2 and 
5. 

The Ultimate Goal 

I thought 16 components was the 
ultimate until I discovered two new 

Text continued on page 63 



OdB ± l.OdB 




±_Li t t t t ■ t t t i t 



500 



1000 
FREQUENCY (Hz) 



1500 



2000 



Figure 6: Passband curves of the ITT 3044 and 3045 hybrid bandpass filters, designed 
specially for DTMF applications. 



Dual 2-bit 
row/column 



4-bit binary 



column 



row 



Digit 


D8 


D4 


D2 


D1 


D8 


D4 


D2 


D1 


1 


• 








1 














2 








1 














1 


3 








1 


1 








1 





4 





1 











1 








5 





1 





1 





1 





1 


6 





1 


1 








1 


1 





7 





1 


1 


1 


1 











8 













1 








1 


9 










1 


1 





1 













1 





1 


1 





1 


* 







1 


1 


1 


1 








# 




1 








1 


1 


1 





A 




1 





1 








1 


1 


B 




1 


1 








1 


1 


1 


C 




1 


1 


1 


1 





1 


1 


D 














1 


1 


1 


1 



Table 3: The two output formats of integrated DTMF receivers showing digit cor- 
respondences. Either a 4-bit binary or a split 2-bit row/column output format may 
be chosen. On the Mostek chips, the format is controlled through the FORMAT 
CONTROL input pin; on the ITT devices, the pin having the same function is 
labeled H/B28. 



58 December 1981 © BYTE Publications Inc 



Start talking 
business 




with your Apple 



COBOL is the most effective business language. 

Apple II is the most friendly business computer. 

CIS COBOL with FORMS-2 brings together the 
best features of COBOL and Apple to enable you to 
deliver the most effective, user-friendly applications. 

Business Programmers: Take the COBOL 
expertise you have acquired on big business 
mainframes, and use it on Apple II to create friendly 
applications that will talk directly to your users - 
where it suits them best, on their own desks. 

CIS COBOL's dynamic module loading gives 
you big application capability and the FORMS-2 
source generator lets you build and modify 
conversational programs from visual screen 
formats, creating much of the code automatically. 

Application vendors: CIS COBOL with 
FORMS-2 steps up the pace for your development 
of the high quality professional application 
packages needed today. And creating them in 
COBOL makes them more maintainable. 



Over half the Apple II 's now being sold are going 
to business or professional users so demand for 
quality applications is growing fast, creating big 
business opportunities for you. 

Stability proven by the US Government. 

CIS COBOL has been tested and approved for two 
consecutive years by the US General Services 
Administration as conforming to the ANSI 74 
COBOL Standard. Apple II under CP/M is included 
in CIS COBOL's 1981 GSA Certificate of Validation 
(at Low-Intermediate Federal Standard plus 
Indexed l-O and Level 2 Inter-Program 
Communication). 

Get your hands on CIS COBOL at your 
Apple dealer. 

Talk business with him now! 

Micro Focus Inc., 1601 Civic Center Drive 
Santa Clara, CA 95050. Phone: (408) 248-3982 . 



MICRO FOCUS 



CIS COBOL with FORMS-2 for use on the Apple II with CP/M is an Apple Distributed Product. 
CIS COBOL and FORMS-2 are trademarks of Micro Focus. CP/M is a trademark of Digital 
Research. Apple II Is a trademark of Apple Computer. 



Circle 109 on inquiry card. 



Circle 135 on Inquiry card. 



The 

Ultimate IEEE 
S-100 Memory 
Would... 

□ BE NONVOLATILE holding data 
for up to eight years with the 
power off. 

□ RUN AT 6 MHZ 

without wait states. 

□ RUN IN 8 OR 16-BIT 

systems with 8 or 16-bit 
wide data paths. 

□ HAVE EXTENDED 24-BIT 

ADDRESSING and bank select. 

□ HAVE DYNAMICALLY 
MOVABLE WRITE 
PROTECT AREAS to prevent 
accidental erasure or programs 
and critical data. 

□ GENERATE POWER-FAIL 

interrupts for orderly system 
shutdown & power failure 
recovery. 




...Available Now 
from Dual Systems 

The Dual Systems CMEM 
memory boards combine high- 
speed CMOS memories with new 
5-10 year lithium batteries to give 
you the nonvolatility of an EPROM 
board while retaining the instant 
writability of a high-speed 
read/write RAM. These industrial 
grade boards are ruggedly built 
and are burned-in for 200 hours. 

□ CMEM-32K, 32K-byt.es . . . $895 

□ CMEM-16K, 16K-bytes .... $795 

□ CMEM-8K, 8K-bytes $695 

OEM and Dealer pricing is available. 

Sales representatives in most metropolitan areas. 




system reliability/system integrity 

DUAL SYSTEMS 
CONTROL CORPORATION 

720 Channing Way, Berkeley, CA 94710 
(415) 549-3854 • TWX 910 366-2035 



Pin 


Name 


Description 


1 


MON OUT 


Provides signal that is one-tenth differential input 


2 


TP 


Internal Test Point 


3 


v P 


Positive Supply Voltage 


4 


Gl 


Gain Adjust I 


5 


Gil 


Gain Adjust II, resistor from Gl to Gil increases sensitivity (see 
table 4b) 


6 


Gill 


Gain Adjust III, resistor from Gil to Gill decreases sensitivity (see 
table 4b) 


7 


v N 


Negative Supply Voltage (ground) 


8 


NC 




9 


XOUT 


Crystal Out, 3.579 MHz crystal connected from pin 9 to pin 10 


10 


XIN 


Crystal In (Tie to V P if external oscillator is used) 


11 


XEN 


Enable Internal Oscillator. Tie to V P if crystal is'used, tie to V N if 
external oscillator is used. 


12 


ATB 


Alternate Time Base. If XEN is high, ATB is clock output. If XEN 
is low, ATB is clock input from other 3210. 


13 


DV 


Data Valid. Indicates tone burst has been detected by going to 
high logic level. Will remain high until tone is removed or CLRDV 
is pulsed high. 


14 


CLRDV 


Clear Data Valid. Pulsing this pin to a high logic level will reset 
DV. 


15 
16 
17 
18 


D8 
D4 
D2 
D1 


Digital outputs. These outputs provide a coded represen- 
tation of the signal received when DV is high. The code is 
selected by H/B28 (pin 19). 


19 


H/B28 


Code Select. When tied to V P , the output on lines D8 through D1 
is hexadecimal; when tied to V N , the output is binary-coded 2 of 
8. 


20 


EN 


Output Enable. When this pin is a logic high, the output codes on 
lines D8 through D1 are enabled. When this pin is a logic low, 
outputs D8 through D1 assume a high-impedance state. 


21 


IN1633 


Inhibit 1633 Hz. When this pin is at a logic high, the 3210 will 
detect only digits through 9, #, and *. When at a logic low, the 
3210 will detect all 16 tone-pair combinations. 


22 


NC 




23 


RING 


More negative of the two analog inputs 


24 


TIP 


More positive of the two analog inputs 



Table 4a: Description of the pin functions of the ITT MSD3210 integrated tone 
decoder/ receiver. 



Gain Increase 


Resistance GI-GII 


Gain Decrease 


Resistance GII-GIII 


3.0 dB 


100k 


3.5 dB 


1 megohm 


5.3 


50k 


6.3 


470k 


7.1 


33k 


8.0 


330k 


9.3 


22k 


10.3 


220k 


11.6 


15k 


12.7 


150k 


14.3 


10k 


15.6 


100k 



Table 4b: Varying amounts of signal gain may be obtained from the adjustable-gain 
stage of the ITT MSD3210 by connecting different values of resistance, shown here, 
to the three gain-adjust input pins. 



60 December 1981 © BYTE Publications lnc 



FORTH 



«<FOR/MAT»>™ 

SCREEN EDITOR 

and 



KV 33 Corporation 

P.O. Box 27246 / Tucson, Arizona 85726 



DATA ENTRY SYSTEM 

An absolute must for the 
serious FORTH programmer.., 






Current tab over 
value and CP 
location displayed at 
all times. 



Deupdate command 
included along with 
other utilities. 



Works very well with 
memory mapped 
video. 



Maintains its own 64 
byte buffer that never 
changes location. 
Any text transferred 
to it via CTRL- Twill 
remain until system 
shut-down or another 
CTRL-T transfer. 




Message displayed 
when iNsert mode is 
toggled on via 
CTRL-N. 



A special formatted 
list routine included 
for printer output. 



CP is never allowed 
outside of the 
FORTH screen 
boundary. 



Less than two lines of 
code need to be 
changed to work on 
most any terminal. 
(Clear screen code 
and the XY cursor 
addressing.) 



Screen formal for the standard CRT version. 



List of commands: These commands are for the TeleVideo 912, but 
are very easily modified to match the character 
set or special functions keys on any terminal. 



DEL 
CTRL-L 
CTRL-H 
CTRL-G 



CTRL-J 



CTRL-E 
CTRL-S 



Delete — Delete character to left and move CP left one position. 
Right arrow — ^ — CP advances one position to right. 

Left arrow ^ CP advances one position to left. 

Get character — Character at CP location is erased when all text on 

line to right is moved left one position. The end of line character 

location is blanked out. 

Tab over to next tab location — The tab over count is stored as a 

variable and can be changed to any number between and 63. 

CP will advance to next location each time command is given. 

Down arrow — CP moves down one line and maintains same 

column position. 

Up arrow — CP moves up one line and maintains same column 

position. 

Erase line — Line occupied by CP will be completely erased. 

Spread open — All lines below and including CP line move down 

one line. . .last line is lost. 

. .the editor 



CTRL-T Transfer — Transfer the CP line to the editor buffer. 

buffer contents will be overwritten. 
CTRL-R Read — Read a copy of the editor buffer into the line occupied by 

CP. . .editor buffer contents remain unchanged. 
CTRL-D Delete and close — All lines below CP move up one line and last line 

is erased to all spaces. . .original line is overwritten. 
CTRL-C Clear — All lines below and including line occupied by CP are 

erased to all spaces. . .total screen is erased if CP is on first line. 
CTRL-B Beginning of line — CP moves to leftmost position on line. 
HOME Home — CP moves to top leftmost position of Forth screen. 
RETURN Return key — Do a carriage return line feed. 
CTRL-Z Zap to end of line — All text from CP to end of line is erased. 

CTRL-F Find — Search screen starting at CP position for a string that 
matches the contents of the editor buffer. (This routine is 
purchased separately.) 

CTRL-N iNsert mode is toggled on or off — Character input at CP location 
will push text on current line to right one position. . .last character 
on line will be lost. . .delete, valid character entry, control-G and 
control-Narethe only commands recognized while in iNsert mode 
. . .control-G works the same. . .delete not only deletes the 
character to the left, but also moves text from CP to end of line left 
one position. . .control-N will toggle iNsert mode off. 

CTRL-Q Quit editing and return to Forth. 



Three listings included. The first listing is for use with a standard 
CRT terminal. The second and third listings are for use with a 
Memory Mapped Video (16x64 and 24x80). 

The above example reflects a transfer of line 3 to the editor buffer via 
control-T. The editor buffer contents can be read into any line 
occupied by Character-Pointer via control-R. This buffer never 
changes location and its contents are displayed at all times. It is very 
handy for relocating lines or moving lines from one screen to 
another. 

Please note the "NSERT/ON" message displayed at the upper right 
to indicate that the iNsert mode has been toggled on via CTRL-N. 
This message is erased when iNsert mode is toggled off. 

The TAB over count is stored as a variable so it can be changed at 
any time. The current value is always displayed to the right of TAB='. 

CP location is maintained within the boundaries of the Forth screen 
at all times. Its value is always displayed to the right of 'CP='. 

Memory requirements are well under 2K. 

All code conforms to the Forth-79 Standard. Each line of code is fully 
explained and flow-charted (Forth style) for easy modification. 

Bomb proof. . .all unused control codes are trapped. 

Must be used with a CRT that has cursor addressing or with a 
Memory Mapped Video. 

The FINDWD package is sold separately but space has been 
reserved in the EDitor for future insertion. It will prove to be an 
invaluable tool for finding a word or words in a screen or searching a 
wide range of screens. It is fully documented and flow-charted. We 
spent a tremendous amount of time on this routine and have cut the 
search time down to under a second per screen (for a screen that is 
already in memory). 

Send check or money order in the amount of $50.00, payable to 
KV33 Corporation, and receive complete source code, flow-charts, 
documentation, and instructions for bringing up on your system. 

FINDWD package is $35.00. Must have the above screen editor to 
operate. 

Please include extra postage for overseas orders, shipping weight 10 oz. 



> copyright 1981 KV33 Corporation • P.O. Box 27246 • Tucson, Arizona 85726 • (602) 889-5722 



Circle 215 on inquiry card. 



FIL TER 



LIMITED 



TONE RECEIVER 



ANALOG 

DTMF INPUT 

FROM 

TELEPHONE-LINE 

INTERFACE 

COUPLER 



20 



HIGH-GROUP 
FILTER 



IN 



OUT 



IC1 

ITT 3045 



16 



20 



LOW-GROUP 
FILTER 



OUT 



IC2 

ITT 3044 



16 



1N914 

-w- 



1N914 

-w- 



100K 
— VW— 




IK 



1N914 

-w- 



1N914 



100K 

— vw— 




J 



04 

D3 

IC4 

MK5102N-5 02 

Dl 



STROBE 



LG V- 

OSC IN OSC OUT 



+5V 



10 



-O 04 
-D>D3 
HZ>02 



DIGITAL 
OUTPUT 



-O STROBE 



<3 



-?? 



HIH 

3.579545 MHi 
CRYSTAL 

Figure 7: Schematic diagram of a DTMF-receiver circuit that employs the ITT 3044 and 3045 hybrid bandpass filters and the MK5102 
decoder. 



TIP- 



RING ■ 



"N" 



24 



23 



M0N OUT 

1 




VOLTAGE 
REG 



DIAL-TONE- 
REJECT 

FILTER 



-•• VREF 



Gi I Gi 



l~" 






ADJ 

GAIN 

STAGE 



CMOS 

LSI 

DECODER 



10 



XIN 



XOUT 

I 
i 



' jrij J 3.58 MHz 

luT CRYSTAL 



'1 



15 



17 



13 



19 



20 



21 



12 



D8 
D4 



02 
Dl 



CLRDV 
H/B28 



EN 

IN 1633 



XEN 
ATB 



Figure 8: Block diagram of the ITT MSD3210 hybrid thick-film-technology DTMF decoder/ receiver shown in photo 6 on page 68. 

62 December 1981 © BYTE Publications Inc 



Circle 136 on inquiry card. 



Number Type 


+ 5 V GND 


-12 V +12 V 


IC1 ITT3045 


18 


13 5 


IC2 ITT3044 


18 


13 5 


IC3 MC1458 




4 8 


IC4 MK5102N-5 


1 6 




Power connections for 


circuits shown 


in figure 7. 



+ 12V 
A 



TELEPHONE-LINE 

INTERFACE 

COUPLER 



23 



21 



/77 



20 



19 



11 



EN H/B28 XEN Vp 
TIP Dl 

D2 
RING D4 

08 
ITT 3210 

IN 1633 DV 

CLRDV 

V N 



XIN 



XOUT 



18 



Ol 



17 



-o 



16 



15 



-o 

-o. 



OUTPUTS 



13 



-O STROBE 



3.579546 MHz 
CRYSTAL 

Figure 9: Schematic diagram of connections to the MSD3210 for use as a DTMF 
receiver. 



Text continued from page 58: 
integrated circuits from ITT, the 
MSD3210 and MSD3201. The 
MSD3210 is a hybrid DTMF tone 
receiver that uses thick-film 
CMOS/LSI technology. The output 
is a 4-bit code directly compatible 
with standard CMOS logic. As 
shown in the block diagram of figure 
8 on page 62, the input signal is 
received on the telephone-line- 
compatible inputs called, for 
historical reasons, "tip" and "ring." 
(This compatibility does not, 
however, necessarily mean that you 
can connect it directly to a telephone 
line and still be in compliance with 
telephone-company tariffs.) Each line 
is protected for a voltage range from 
-200 to +200 volts, and the two 
provide a balanced differential input 
impedance of 600 k ohms. 

The output of this rirst stage is 
passed through a high-pass and dial- 



tone-reject filter into an adjustable 
gain and attenuation stage. Next, the 
CMOS LSI decoder circuit provides 
bandsplitting, tone detection (by the 
digital zero-crossing method), and 
timing functions. The output code is 
selected by the H/B28 (hexadecimal 
or binary-coded 2-of-8 select) line. 
The code relationships are shown in 
table 3. When the DV (output strobe) 
line goes high, a tone pair is present 
on the input lines and the output data 
levels are valid. Table 4 on page 60 
describes the functions of all the 
MSD3210's pins. A complete DTMF- 
receiver circuit, as shown in figure 9 
on page 63, requires only two com- 
ponents. 

While my personal choice for a 
DTMF receiver right now is the 
MSD3210, ITT also makes a true 
single-chip CMOS DTMF receiver (as 
opposed to a hybrid package) 

Text continued on page 68 



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December 1981 © BYTE Publications Inc 63 



ANALOG IN 




Figure 10: Block diagram and pinout specifications of the ITT MSD3201 CMOS DTMF-decoder/ receiver chip shown in photo 7. 
Because of the inherent ease of manufacture of CMOS components, the price of the 3201 may be expected to fall. 

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64 December 1981 © BYTE Publications Inc 



Circle 263 on inquiry card. 



TIMING 
CIRCUITRY 



DV STROBE 



DATA STROBE 



OUTPUT 
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16 
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14 
13 
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02 

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December 1981 © BYTE Publications Inc 65 



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Text continued from page 63: 
designated the MSD3201, the internal 
structure of which is shown in the 
block diagram of figure 10 on pages 
64 and 65. It uses a slightly different 
technique to process the DTMF 
signal. After the usual 60-Hz-reject 
and bandsplitting filters, the 3201 



uses eight bandpass filters to detect 
the tones by analog means (remember 
the seven LM567s?), rather than the 
digital method employed in the 3210. 
Other than that, its operation is 
similar to the 3210's. 

The MSD3201 is aimed at high- 
volume users. In common with any 



DIAL TONE 
REJECT 
FILTER 



ADJ 
GAIN 
STAGE 



ITT MSD 

3 210 



CMOS 

LSI 

DECODER 



O 

10XIN 



o 

9XOUT 



Block Diagram ITT 3210 



_jj |!_J 3.58 MHz 
il—Ji CRYSTAL 




Photo 6: An even more compact DTMF receiver can be made using the ITT 
MSD3210 hybrid thick-film-technology DTMF decoder/receiver chip. A single 
dual-inline package and a crystal form the complete receiver, at a cost of about 
$70. 



3201 

Integrated DTMF Receiver 




ption 

3201 is a complete Dual Tone Multiple 

icy (DTMF) receiver detecting a selectable 

12 or 16 standard digits. No front-end 
ing is needed. The only externally required 
>nts are an inexpensive 3.58-MHz television 



Photo 7: Most future high-volume designs will use advanced devices such as this 
ITT MSD3201 single-chip CMOS DTMF decoder/ receiver. 



integrated circuit of this type, its price 
will drop in volume production. 

Making the Connection 

Before you decide to build one of 
these circuits, be aware of the restric- 
tions in attaching it to the telephone 
line. Like a direct-connect modem or 
automatic telephone-answering 
device, any of these circuits must be 
connected through an FCC- (Federal 
Communications Commission) ap- 
proved line-protection transformer or 
coupler. This line-interface device is 
installed to protect the telephone 
system from half-asleep ex- 
perimenters who might short 115 
volts AC onto the telephone lines. 
The coupler generally consists of a 
600-ohm matching transformer and 
some overvoltage-protection com- 
ponents. If you plan on experiment- 
ing with the telephone lines, the 
telephone company will install a 
coupler for a low monthly charge. 

It is not absolutely necessary to 
directly connect to the telephone 
lines. In his book Telephone Ac- 
cessories You Can Build (reference 2), 
Jules H. Gilder describes the construc- 
tion of an automatic answering 
device using an acoustic-coupling 
method. A small microphone hears 
the telephone ringing and triggers a 
solenoid that lifts the handset off the 
cradle. A speaker and microphone 
fastened over the mouthpiece and 
earpiece of the handset provide a link 
to the user's answering device. For 
casual use, this sort of kluge can be 
effective. 

Other Possible Approaches 

I hope you can see the benefits of 
using the MSD3210 and 3201 DTMF 
receivers because of the effort re- 
quired to construct your own 
separate-component filters. Of 
course, I have a tendency to lean 
toward hardware solutions to any 
problem and avoid strenuous pro- 
gramming. If, however, you hold a 
black belt in machine-language pro- 
gramming, you might try an all- 
software approach. Conceivably, 
you could write an FFT (fast-Fourier- 
transform) routine to detect the 
DTMF frequencies. Personally, I'd 
rather do something else between ar- 



68 December 1981 © BYTE Publications Inc 



Circle 435 on inquiry card. 



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tides than wrack my brain while star- 
ing at a video display. I'll just buy a 
few more chips. 

One place software might work 
well is the DTMF-encoding function. 
I haven't tried that because I've 
always envisioned myself stepping in- 
to a phone booth in Butte, Montana, 
and "talking" to my computer 
through either the built-in Touch 
Tone keypad or a small handheld 
DTMF encoder. Software-generated 
tones might not be very portable. If 
your application is less mobile, you 
might try synthesizing the DTMF 
waveforms with software timing 
loops or through a simple D/A con- 
version. An informative article by 
John Renbarger entitled "A 
Telephone-Dialing Microcomputer" 
that deals with D/A-conversion 
signaling on a KIM-1 system was 
published in the June 1980 BYTE 
(page 140). 

In Conclusion 

Through a series of circuits ranging 
from a hundred components down to 
two, I have attempted to demonstrate 



both hobbyist and commercial 
decoding techniques. The choice of 
which one to build is generally a com- 
promise between assembly time and 
component cost. If you have a lot of 
spare time and an ample junk box, 
you might try building the 
100-component circuit. Designers 
working on commercial applications, 
on the other hand, would definitely 
opt for the latter. In my own case, 
wiring all those resistors and 
capacitors together once was enough. 
I will stay with the ITT MSD3210 and 
gladly pay the difference. 

Inasmuch as it may be a while 
before I have an intelligent conversa- 
tion with my computer, and 
technology moves very fast, perhaps 
by the time I am ready to fully imple- 
ment remote interaction with my 
computer I will discard DTMF signal- 
ing in favor of voice recognition. 

Next Month: 

In case you're interested in trying 
to generate DTMF waveforms by 
D/A conversion, we'll look at the 
basic principles of digital-to-analog 



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and analog-to-digital conversion. Oh 
yes, you may find it interesting for 
other applications, too. ■ 



References 

1. Berlin, Howard M. Design of Phase- 
Locked Loop Circuits, with Experiments. 
Indianapolis: Howard W. Sams, 1978. 

2. Gilder, Jules H. Telephone Accessories 
You Can Build. Rochelle Park NJ: Hayden, 
1976. 

3. Hilburn, John L. and David E. Johnson. 
Manual of Active Filter Design. New York: 
McGraw-Hill, 1973. 

4. Lancaster, Don. Active Filter Cookbook. 
Indianapolis: Howard W. Sams, 1978. 

5. Renbarger, John. "A Telephone-Dialing 
Microcomputer." BYTE, June 1980, page 
140. 



Editor's Note: Steve often refers to previous 
Circuit Cellar articles as reference material for 
the articles he presents each month. These ar- 
ticles are available in reprint books from BYTE 
Books, 70 Main St, Peterborough NH 03458. 
Ciarcia's Circuit Cellar covers articles appear- 
ing in BYTE from September 1977 through 
November 1978. Ciarcia's Circuit Cellar, 
Volume II presents articles from December 
1978 through June 1980. 



The following items are available 
from: 

The MicroMint Inc. 
917 Midway 
Woodmere NY 11598 
telephone (516) 374-6793 

1. ITT MSD3210 Hybrid DTMF Tone 
Receiver $66 

2. 3.579545 MHz crystal (for use with 
item 1) $4 

3. ITT MSD3201 CMOS DTMF Tone 
Receiver $95 

4. ITT 3044/3045 Group Filters (one 
pair) $60.80 

Items 1 and 2 will be shipped from 
stock. For items 3 and 4, call to deter- 
mine availability. 

Please include $1.50 for shipping and 
insurance. New York residents please 
include 7% sales tax. For orders to be 
shipped outside the United States, 
please add $6. 



To receive a complete list of Oarcia Cir- 
cuit Cellar kits available from The Micro- 
Mint, circle 100 on the inquiry card. 



70 December 1981 © BYTE Publications Inc 



Circle 84 on inquiry card. 



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run on most microcomputers. 
Especially useful in small busi- 
ness and household applications. 
^Generalized BASIC) #38-1, $15.99 □ 



<£ 



Osborne 

CP/M "User Guide 

by Thorn Hogan 

The most complete and up-to- 
date CP/M book you can find. It 
will make your first use of CP/M 
easy. If you already own CP/M, it 
will help you modify your system. 
#44-6, $12.99 □ 

CBASIC "Users Guide 

by Adam Osborne, Gordon Eubanks 
and Martin McNiff 

Co-authored by Gordon Eu- 
banks, the creator of CBASIC, 
this is more than a self-teaching 
textbook, it is the definitive ref- 
erence of the CBASIC language. 

#61-6, $15.00 D 




Want g?T 



BUSINESS 
BOOKS 

by Lon Poole and co-authors 

Osborne's three business sys- 
tems are renowned for excel- 
lence in design and documenta- 
tion. Our books explain in de- 
tail how to use the programs. 
They contain complete program 
listings, supporting technical 
documentation, and specific in- 
formation on changing and 
installing the programs. 

Payroll 

with Cost Accounting 

#22-5. $20.00 D 

Accounts Payable and 
Accounts Receivable 

#23-3, $20.00 D 

General Ledger 

#24-1, $20.00 □ 

ASSEMBLY 

LANGUAGE 

PROGRAM 

SERIES 

by Lance Leventhal and co-authors 

You needn't know anything 
about assembly language to use 
these books. Each one is a 
straightforward, self-teaching 
textbook that is both precise and 
easy to understand. 

68000 #62-4, $16.99 D 

6809 #35-7, $16.99 D 

6502 #27-6, $16.99 D 

Z80 #21-7, $16.99 D 

Z8000 #36-5. $19.99 a 

6800 #12-8. $15.99 □ 

8080A/8085 .... #10-1. $15,990 
The 8086 Book 

by Russell Rector and George Alexy 

Part assembly language text and 
part hardware reference, this 
book covers all of the 8086's 
most important features. 

#29-2, $16.99 D 

^ INTERFACE 

Interfacing to S-100 (IEEE 
696) Microcomputers 

by Sol Libes and Mark Garetz 

Describes the S-100 Bus with 
unmatched precision. Covers 
mechanical and electrical design, 
logical and electrical relation- 
ships, bus interconnections, and 
much more. #37-3, $15.00 a 







PET and the IEEE 488 Bus 
(GPIB) 

by E. Fisher and C.W. Jensen 

Provides chapters on all aspects 
of the General Purpose Interface 
Bus. Includes lines, signals, 
specifications, and much more. 

uj #31-4, $15.99 D 

Microprocessors for 
Measurement and Control 

by D.M. Auslander and P. Sagues 
Learn to design mechanical and 
process equipment using micro- 
processor based "real-time" com- 
puter systems. This book allows 
readers (even those unfamiliar 
with machine or assembly lan- 
guage) to initiate projects. 

#57-8, $15.99 □ 



MICRO- 
ELECTRONIC 
REFERENCES 

Osborne 4 & 8 Bit 

Microprocessor 

Handbook 

by Adam Osborne and Gerry Kane 
The one source for complete, 
objective and accurate informa- 



tion on 4 and 8 bit microproces- 
sors. This book describes virtu- 
ally every 4 and 8 bit micropro- 
cessor on the market today and 
allows you to evaluate any de- 
vice or combination of devices. 

#42-X, $19.95 D 

Osborne 16-Bit 
Microprocessor Handbook 

by Gerry Kane and Adam Osborne 

A total reference book on 
virtually every 16-Bit micropro- 
cessor, this book permits objec- 
tive evaluation and comparison 
of these new devices. 

#43-8, $19.95 D 

An Introduction to 
Microcomputers: 
Volume 3 - Some Real 
Support Devices 

by Gerry Kane and Adam Osborne 

Available with or without 3-ring 
binder or updates. Each device 
is described in detail, including 
an analysis of the best uses for 
that device. Book - #18-7, $15.00 □ 

Binder - #19-5, $6.99 □ 
Six Updates - #98, $25.00 □ 



HANDBOOKS 

68000 Microprocessor 
Handbook 

by Gerry Kane 

This handbook offers more in- 
formation about the 68000 than 
the manufacturer's data sheets. 



CRT Controller Handbook 

by Gerry Kane 

Describes five devices in the 
same thorough detail you'll find 
in Volume 3. Contains 13 tables 
and 149 separate illustrations. 

#45-4, $6.99 D 

8089 I/O Processor 
Handbook 

by Adam Osborne 

A complete presentation of the 
8089. The 8289 Bus Arbiter is 
also described with the same 
careful attention to design and 
application. 

#39-X, $6.99 □ 



ORDER FORM 

Book Title, Book #, Price 



Osborne/McGraw-Hill Dept. B20 
630 Bancroft Way, Berkeley, CA 94710 

Name 

Add ress 



Call Toll Free: 800-227-2895 

in California (415) 548-2805 



m 



City/State/Zip 

Plus: Q .75/item 4th class □ $1.50/item UPS □ $2.50/item Air Mail □ $10.00/item Overseas 
(California residents add applicable tax.) 

Total amount enclosed $ or charge my □ Visa 



Card #_ 



D Mastercharge 
Exp. Date 



Circle 326 on Inquiry card. 




Olympic Decathlon 



David A Kater 

POB 1868 

La Mesa CA 92041 



Photo Is The javelin throw (TRS-80 Model I version) 



V^^/kay, you armchair 
athletes, Microsoft has 
a program for you. 
Slide your easy chair 
over to the computer 
and prepare to compete 
in an Olympic Decath- 
lon — 10 events requir- 
ing speed, timing, and 
agility. 

Game of the Year 

When I first heard of 
this program, it sound- 
ed fairly bland. With its 
dull name, I just knew 
it couldn't compare to 
"Super-Intergalactic- 
Cosmos-Blasters . " 

Luckily, I happened 
to witness the presenta- 
tion of the Creative 
Computing Game of 
the Year award at the 
West Coast Computer 
Faire. Guess which pro- 
gram took the honors 
for 1980? That's right: 
Olympic Decathlon, by 

Tim Smith. At the pre- 
sentation Tim gave us a firsthand demonstration of his 
ingenious creation. When the presentation ended, I 
bought a copy and raced home to try it on my computer. 
I wasn't disappointed; the program exceeds its promise. 





Photo 2: The javelin throw (Apple II version). 



Olympic Decathlon 
is a remarkable simula- 
tion of the two-day 
event at the Olympic 
Games. It includes the 
100-meter dash, long 
jump, shot put, high 
jump, and 400-meter 
dash on the first day. 
The second day fea- 
tures the 110-meter 
hurdles, discus throw, 
pole vault, javelin 
throw, and 1500-meter 
run. The winner of this 
combined event is con- 
sidered the world's best 
athlete. After you par- 
ticipate in the computer 
version of the decath- 
lon, you'll understand 
why. 

Each event is dis- 
played in superb ani- 
mated graphics that 
you control via the 
keyboard. The appro- 
priate keys necessary 
for each event are dis- 
played on the screen 

before each trial. These instructions are sufficient to 
explore each event, but you may wish to consult the 
manual for ways to approach some of the 
more difficult ones. 



74 Deccmbtr 1981 © BYTE Publications Inc 



Systems IE€x 



a total business system. 



JOB COSTING MENU 

1. TRANSACTION ENTRY/DATE 

2. JOB/TASK TABLE MAINTENANCE 

3. JOB COST FILE MAINTENANCE 

4. JOB COST REPORTING 

5. EMPLOYEE TABLE MAINTENANCE 

6. RETURN TO MASTER MENU 

SELECT |1-6|? 



SYSTEMS II EX 
MASTER MENU 

1. INVENTORY 7. CHART OF ACCTS. 

2. PAYABLES 8. VENDOR MAINT. 

3. RECEIVABLES 9. CUST. MAINT. 

4. PAYROLL 10. CHANGE DATE 

5. LEDGER 11. SYS/BACKUP 

6. JOURNAL 12. STOP PROCSSG. 

13. OPTIONAL PROCSSG. 
L_ SELECT 11-13)7 



DATABASE MENU 

1. FILE MAINTENANCE 

2. REPORTS/REPORT MAINT. 

3. UTILITIES 

4. RETURN TO SYSTEM MENU 

SELECT (M|? 



ACCOUNTS PAYABLES MENU 

1. FILE MAINTENANCE 

2. PAYMENT SELECTION 

3. PRINT CHECKS AND REGISTER 

4. MONTH END 

5. RETURN TO MASTER MENU 

SELECT |1-5|? 



RECEIVABLES SYSTEM MENU 

1. FILE MAINTENANCE 

2. RECEIPT OF PAYMENTS 

3. GENERATE BILLING 
"10NTH END 

i. PAST DUE REPORT 

6. APPLY MONTHLY INTEREST 

7. RETURN TO MASTER MENU 
'^ SELECT [1-7)7 



LEDGER SYSTEM MENU 

1. FILE MAINTENANCE 

2. BAL SHEET/INCOME STATEMENT 

3. YEAR END PROCESS 

4. RETURN TO MASTER MENU 

SELECT (1-4)7 



INVENTORY SYSTEM MENU 
TIME DATE 

1. FILE MAINTENANCE 

2. POINT OF SALES 

3. REORDER REPORT 

14. RETURN TO MASTER MENU 
i SELECT |1-4|? 



r STATE 

PAYROLL MENU 

1. MISC/TAX TABLE MAINT. 

2. TRANSACTION FILE 

3. MISC. PAY/DEDUCTION FILE 

4. EMPLOYEE MASTER FILE 

5. CALCULATE/PRINT CHECKS 

6. PRINT W2s 

7. RETURN TO MASTER MENU 
SELECT (1-7|? 



SYSTEMS II EX — EX for EXTENDED 
PERFORMANCE. Westware brings you the 
most completely integrated and simplest to 
use business software for your Apple 
Computer. The SYSTEMS II EX is complete 
with an integrated Database. Yes! The DBII 
Database can move your system's files into 
Database format for customized reports or 
labels. 

Although the SYSTEMS II EX is a fully 
integrated system, you may purchase 




individual modules and later add additional 
modules, such as Job Costing for 
contractors. The power of our system is in 
the KSAM Firmware card that plugs into the 
Apple. This card permits high speed 
searches and eliminates running sort 
routines to get your files in order. 

SYSTEMS II is available on 5'A" drives, and 
also on the Corvus hard disk. A Corvus 
based system will give you the power and 
capacity that challenges larger computers. 



COMING SOON — Cash flow analysis with 
graphics, Database II with graphics, and Bill 
of Materials for small manufacturers. 

CURRENT OPTIONS AVAILABLE - Job 
Costing, Cycle Invoicing, Order entry, and 
Layaway. 

All Checks, statements and invoices use 
NEBS forms. 

Dealer and OEM inquiries invited. 

Apple is a trademark of Apple Computers. 



Systems!! €x 



2455 S.W. 4th Ave. 
Suite 2 

Ontario, OR 97914 
(503) 881-1477 



Circle 436 on inquiry card. 




Yes. please send 
me your Systems II 
Demo Package. 



2% D Yes, I would like to sample your software. Please 
send me the Systems II Demo Package. My check 
for $25 is enclosed. 




2455 S.W. 4th Ave. 
Suite 2 

Ontario, OR 97914 
(503) 881-1477 



Name. 



Title 



Company Name. 
Address 



City 



State . 



Zip. 




., Afa danrp. 




Name 


Language 


Olympic Decathlon 


Z80 machine code (TRS-80); 




6502 machine code (Apple) 


Type 




Game/simulation 


Computer needed 




16 K TRS-80 Model I, Level 


Manufacturer 


I or II — tape version; 32 K 


Microsoft Consumer 


TRS-80 Model I, one disk 


Products 


drive (two needed to do 


400 108th Ave NE, Suite 200 


backup); 48 K Apple II or 


Bellevue WA 98004 


Apple II Plus, one disk drive 


(206) 454-1315 


(two needed to do backup), 




and two game controller 


Price 


paddles 


$24.95 






Documentation 


Author 


48 pages for TRS-80; 


Timothy W Smith 


39 pages for Apple 


Format 


Audience 


5Vi-inch floppy disk or 


Armchair athletes of 


cassette (TRS-80 only) 


all nations 



The events require fast reflexes, good coordination, 
timing, and lots of practice. There is a practice mode for 
each event so that you can polish your technique before 
the start. 

Competition 

Olympic Decathlon may be played alone or with 
others. When you are ready to begin, the computer asks 
for the number of competitors. Up to eight athletes may 
compete in the TRS-80 version; as many as six in the 
Apple version. Playing alone, you will strive to better 
your previous performances. When several people par- 
ticipate, the game develops an entirely different 
character. Scores take on new meaning as the com- 
petitors jockey for position in the standings. Head-to- 
head confrontations in the running events add to the 
drama. 

The Simulation 

Smith has captured the flavor of the Olympic Games 
on magnetic media. With a bit of imagination, you may 
relive those days on your hometown track, where you 




R 2 l/0 

S-100 ROM, 

RAM & I/O 

BOARD 



Building Blocks for 
Microcomputer Systems, 
Dedicated Controllers 
and Test Equipment. 




ECT's R 2 l/0 is an S-100 Bus I/O Board with 3 Serial 
I/O Ports (UARTs), 1 Parallel I/O Port, 4 Status Ports, 
2K of ROM with the 8080 Apple Monitor Program and 
2K of Static RAM. 

$295.00 




RM-10 
S-100 

RACK MOUNT 
CARD CAGE 



ECT's RM-10 is a rack mount 10 slot Card Cage with 
Power Supply, consisting of an ECT-100 rack mount 
Card Cage (19"W x 12.25"H x 8"D), the MB-10 Mother 
Board (with ground plane and termination) all 10 
connectors and guides and the PS-15A Power Supply 
(15A @ 8V, 1.5A @ ± 16V). 



$295.00 



Specializing in Quality Microcomputer Hardware 

Industrial • Educational • Small Business • Personal 

Card Cages, Power Supplies, Mainframes, CPU's, Memory, I/O, OEM Variations 



ELECTRONIC CONTROL TECHNOLOGY 



763 Ramsey Ave., Hillside, NJ 07205 



(201) 686-8080 



76 December 1981 © BYTE Publications Inc 



Circle 145 on inquiry card. 




BROADEN YOUR HORIZONS 




UVKON proudly announces 

( )PTIMUM.'" OPTIMUM is an easy 10 
use, total concept data management 
program for ( P/M* and MP/M '" systems. 
Breaking through traditional DMS 
harriers, OPTIMUM provides large scale 
data management capability to broaden 
your computer horizons. Developed for 
individual computer users and applica- 
tions builders, OPTIMUM supports 
user-defined forms and files, dictionaries, 
powerful repotting, storage efficiency, 
speed and unique cross referencing. 
Everything you want in data management 
is now complete in one system. 

USER-DEFINED 

FORMS AND FILES 

With OPTIMl /M, implementing an 
application is simple. The user defines 
screen forms to fit the data and describes 
how the data is to be stored. Once this is 
complete, data entry may begin. Input 
editing, validation and cross-referencing 
during data entry extend OPTIMUM'S 
range. If the need exists. OPTIMUM can 
handle complex or multiple screen forms 
for the same file. Screen forms may be 
modified and expanded as needed. 

DICTIONARIES 

( )PTIMUM maintains a dictionary of 
terms for each file. This dictionary 
contains information on each data 
element in the file and describes 
operations to be performed. Alterations 
and additions to the dictionary may be 
made as required. 



MICRO-ENGLISH REPORTING 

OPTIMUM MicroTNCl.ISH lets the 
user request standard 01 custom reports 
from the OPTIMUM files. Sophisticated 
selecting and sorting capability give 
Micio TNCL1SH all the power of a large- 
scale interactive inquiry processor. A 
dictionary based vocabulary keeps the 
uset interface simple. 

OPTIMUM STORAGE 
EFFICIENCY AND SPEED 

OPTIMUM stores all information in a 
compact variable-length format. 
OPTIMl !M files are designed for 
interactive speed; a single file item may 
be retrieved from among hundreds in 
an instant. 

OPTIMUM DATA 
CROSS-REFERENCINC 

A unique feature of the OPTIMUM 
system allows a user to cross-reference 
data elements. Once information is 
entered, it may be retrieved using key 
words in the data. 

From simple applications to complex 
systems. OPTIMUM manages it all. 
Broaden your horizons using the total 
concept data management system with 
the power of such industry forerunners as 
Prime Information, Honeywell Ultimate 
and Microdata Reality, (all or write 
I IVTON today for more information on 
OPTIMUM. 1-000-.'i25-I637. 

( I7M ,111,1 MI7M .in iTKlemartoul Digital Ratwch. In, 

• 'I' I IMI IM .iiul Mi, i, ,hNI,lN l.ii .■ ii.idnii.ii k-, nlllVION 



UY£OQ 

The Future in Software. 



IJVEON Computer Systems. Inc. 
89° Logan Street 
Denver. Colorado 80203 

Circle 420 on inquiry card. 




can still hear the crowd buzzing about the last race. Now 
it's your turn. Suddenly you are aware only of the 
starter's voice as you toe the starting line. 

ON YOUR MARK 

SET 

GO! 



the vaulting box. Miss the box, and the vault is aborted. 
If the pole plant is successful, and your flying fingers 
have generated enough momentum, the figure will ride 
the pole toward the crossbar — where he must pull up into 
a handstand, just before hitting the bar. Finally, the pole 
must be released before it follows through the crossbar. 
Proper timing is rewarded with SUCCESSFUL VAULTl 



As you frantically tap the keyboard, your animated 
counterpart streaks across the screen. As you near the 
finish line, your fingers scream for relief, but you can't 
give up now; your brother-in-law is gaining. With a final 
burst of energy, you cross the finish line and collapse into 
your chair, savoring a narrow victory. 

The simulation of the actual events is uncanny. Each is 
unique and requires its own combination of timing, tech- 
nique, endurance, coordination, and speed. For example, 
the pole vault demands a healthy dose of all these 
qualities. You begin with a running approach. As the 
graphic figure nears the pit, the pole must be planted in 



Authenticity 

The rules in Olympic Decathlon are virtually identical 
to the real event. For example, in the vaulting events you 
may "pass" on the lower heights and save your energy for 
the tougher ones. If you miss on three consecutive at- 
tempts, you are eliminated from that event. 

The rules are enforced by an eagle-eye official. If he 
determines that you "purposely" knocked down the 
hurdles, you will be disqualified. He also keeps a watch- 
ful eye on the fault line in the javelin throw and long 
jump. And, of course, jumping the gun in a race is forbid- 
den. 




YEAR ROUND SAVINGS plus ; | 

1 A a Christmas Sonus!! 



Energy Savings All Year Round!! 



SciTronics Remote Controllers and Real Time Clocks are saving users 
money all year round. 

Energy bills are being cut by controlling heating, air conditioning, 
lighting, and security systems in homes, offices, stores, and factories. 

You too can save money by simply using your existing computer and 
a SciTronics Remote Controller/Real Time Clock combination as an in- 
expensive energy management system (EMS). Now you have the 
choice of controlling either the light duty BSR X-10 switches sold by 
Sears and others, or the great variety of heavy duty industrial grade 
switches recently introduced by Leviton. With your own EMS you too 
can be saving up to 30% on energy bills. 



Your Christmas Bonus!! 

Adding a SciTronics Remote Controller/Clock combination to your 
computer can allow you to create highly unique Christmas displays. You 
can control sequencing of both indoor and outdoor lights and motorized 
displays in ways only possible with computer control. Thus, your home 
or business can be an exciting eyecatching showplace. 



Contact your local computer dealer for details 

and a demonstration or call SciTronics directly 

about other energy saving products. 




How Does It Work? 

Your S-100, Apple II or TRS-80-I computer prompts the controller to transmit coded 
control signals across existing AC power lines. The signals are received by compact 
remote switches, which replace existing outlets or wall switches. The switches in 
turn control the light or appliance plugged into them. No hard wiring is necessary 
and up to 256 locations may be operated, in either manual or prescheduled real time 
access modes, by a single controller. 



SCJTrOniCS, Inc; 523 So. Clewell St.; P.O. Box 5344; Bethlehem, PA 18015; (215) 868-7220 



78 December 1981 © BYTE Publications Inc 



Circle 375 on inquiry card. 



I 






HI 



m 



WL 



^ Annouro 
TheTableTop Compu 
That Can't BeTopped. 



■ ■ 



■ H 





JtfttL 



jdUUK. 




iHHB 



The 

5000 SX 
with: 



Capacity: 5.5 MB Winchester Plus Two 
Mini Floppies 

if you know our Series 5000 table top 
computer line, you know that good things 
come in small packages. 

Now, with the introduction of the 5000 
SX, big things come in small packages. 

One integrated package can contain two 
double sided, double track density floppies 
plus a 5.5 megabyte Winchester drive. 

Speed: Load 20K in Less Than a Second 

Not only does our high performance 
Winchester subsystem include error 
detection with automatic error correction, 
its extreme speed is comparable to that 
of large main frame hard disk systems. 

A 20K program loads in less than one 
second, about 10 to 12 times as fast as 
a floppy. 

We invite comparison with our com- 
petitors' Winchester implementation then 
you will see how a truly engineered solution 
speeds up your application programs. 

Extras: You'U Be Glad You Have Them 

The 5000 SX comes standard with lots of 
extras, starting with a fully terminated S100 
mother board. Add to that 64K dynamic 
RAM modules, with parity, of course, and 
receptacles for your CRT and Printer that 
turn on with the main power switch. 

Plus, convenient up front power reset 
switch, incoming power line filter and 
much more. 

Software: 

Operating Systems: CP/M, MP/M, 

TurtroDOS 

Languages: BASIC, FORTRAN, COBOL 

Application Packages: FMS-80, 

WORDSTAR, Accounting Plus, all 

tailored to operate on the 5000 SX. 

Quality: So Good, It's Warranted 2 Years 

There isn't room on this page to even 
scratch the surface of the IMS Inter- 
national story. 

However, our 2-year warranty is a dead 
giveaway that we produce rugged, top 
quality, professional equipment. We do 
things right the first time so they don't 
come back to us. 

The truth is, we have fewer returns 
within our 2-year warranty period than 
other manufacturers have within their 
90-day warranty periods. 

For full details and the location of your 
nearby IMS International dealer, call us 
today at (714) 978-6966. Or write: 




NTERNAnONAL 



We Build Computers As If Your Business 
Depended On Them. 

2800 1/x-kheed Way, Carson Citv, NV 89701 
Telex: 910-395-6051 

CP/M & MP/M.TM of Digital Research -TurboDOS, 
TM ofSoftirare 2000 -FMS-80, TM of MR Associates • 
WORDSTAR, TM of MICROPRO -ACCOUNTING PLUS 
TM of SYSTEMS PLUS 

Circle 193 on inquiry card. 




Program Reliability 

The program has exceptionally good error handling. 
User response is strictly controlled to eliminate the accep- 
tance of unreasonable input. The TRS-80 version appears 
to be crash-proof. Try as I might, I couldn't cause the pro- 
gram to crash or even become flustered. Apple II users 
can avoid missing any turns by disabling the RESET key. 

I found one minor logic error in the TRS-80 version. 
When several pairs of people are competing serially, the 
"false starts" are charged by lane rather than by in- 
dividual. By the time this review is published, Microsoft 
will have corrected this problem. Otherwise, the program 
appears flawless. 

Documentation 

The program is accompanied by an instruction booklet 
containing background information about the program, 
the author, and Microsoft. The instructions cover run- 
ning the program, cassette-loading problems, backing up 
the disk (you are allowed one backup), and tape or disk 
replacement. Each event is discussed in detail, and hints 
on technique and strategy are included. 

Hardware Requirements 

Olympic Decathlon is available for the TRS-80 Model I 
and Apple II computers. Each version took about 10 
months to complete. 

The TRS-80 version is available on either cassette or 
disk. The disk version requires 32 K bytes and one disk 



drive. This version is an impressive example of the 
creative animation attainable with low-resolution 
graphics (see photo 1). 

The Apple version is available on disk only. It requires 
48 K bytes, one disk drive, and game paddles. The high- 
resolution color graphics are quite impressive (see photo 
2). The Apple version also plays the Olympic Anthem 
during the opening and awards ceremonies. 

Software Support 

Microsoft is not playing games when it comes to sup- 
port after the sale. Tapes and disks are guaranteed to 
work. If the program fails to load properly, return it to 
the dealer or to Microsoft for a free replacement. If it 
becomes damaged during normal use, Microsoft will 
replace it for $7.50. The disk version allows a single 
backup (requires two drives) to facilitate play while you 
await your replacement disk. 

Conclusions 

Olympic Decathlon is a superior graphics game. A 
well-written simulation that captures much of the flavor 
of the Olympic Games, it is challenging and entertaining. 

While many game programs quickly find their way to 
the "All Played Out" file, the interactive graphics, multi- 
player capability, and unique features of Olympic De- 
cathlon will keep it in your active program library for a 
long time.B 



Missile Defense vs ABM 



Robert Moskowitz 

22200 Tioga Place 

Canoga Park CA 91304 



All is quiet — perhaps too quiet. Then, without warn- 
ing, comes the attack! At first, a single incoming missile 
streaks across the sky. Another follows. Then dozens 
upon dozens, in a crazy-quilt pattern of bomb trajectories 
and defensive streaks, darting and exploding in rapid fire. 
Killer warheads of every description veer relentlessly for 
your cities: ordinary bombs, MIRVs that retarget them- 
selves and multiply without warning, and even "smart" 
bombs that can dodge your most accurate firing. With in- 
creasing speed, they rain down in waves, until your de- 
fenses are taxed to the limit — or more likely overtaxed — 
and your brain circuits sizzle like the cities just fried by 
nuclear fireballs. 



But wait. Nobody is dead. This is fiction. The scenario 
takes place thousands of times every day, at arcades 
across the country and now in thousands of homes 
equipped with Apple computers and color TVs. At the 
arcade, it is Atari's Missile Command — one of the most 
popular games around. At home, you can have two ver- 
sions of the game: Missile Defense(by On-Line Systems) 
and ABM (by Muse Software). All three play a tough, 
fast game with plenty of thrills, sound effects, and 
graphics. This review hopes to differentiate the subtleties, 
the slight distinctions, and the all-important "feel" that 
make for a really rousing atomic warl 

Two notes on these reviews: First, I relied on a panel of 



80 December 1981 © BYTE Publications Inc 




Data communications can open up a whole new world to you and your computer. A world of the future. Now. 
A world full of information resources, time-sharing computer systems, and electronic "bulletin boards." All you 
need for admission to this world is your CP/M- based computer, a modem, and the proper software. That's where we 
come in. We have the proper software. CROSSTALK,™ our smart terminal & file transfer program for CP/M, allows 
you to call into thousands of dial-up computer systems around the world, and communicate with them. REMOTE, 
our CP/M remote console program, allows you to operate your CP/M system from a remote terminal, giving your 
computer added flexibility and usefulness. 

CROSSTALK 

• Allows your computer and modem to communicate with other computers, including other CROSSTALK systems, 
public-access "bulletin board" systems, main frame computers, subscription "Information utilities" such as THE 
SOURCE,™ and much more. 

• Simple, easy to use "plain English" command structure makes CROSSTALK easy to learn, yet provides a powerful 
tool for exchanging files, capturing data, and controlling modem parameters. 

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Circle 19 on inquiry card. 





Photo 1: Muse's ABM game is progress. 



Photo 2: On-Line Systems' Missile Defense game in progress. 



judges, ages five to 19, to play the games extensively and 
give me their opinions. Second, I took Missile Com- 
mand — the original arcade version of the game — as the 
basis for comparison. For better or worse, our judges had 
much more time on that game than either of the home- 
computer versions up for review. So it was natural to see 
which of the home-brew war games compares best with 
the original. 



The Scenario 

All three games offer you a chance to control a missile 
defense system during a savage enemy attack on your 
cities. The game continues until all your cities have been 
destroyed. 

Missile Defense copies the original theme in great 
detail, giving you six nameless cities defended by three 
missile bases. Incoming objects include single bombs, 
MIRV bombs that split and separately retarget 
themselves, and "smart bombs" that move upward and 
horizontally to avoid your defensive missiles. You must 
be very accurate to destroy a smart bomb and very fast to 
counter a MIRV attack. 

The attacks tend to come in waves, initially slow, then 
faster, splitting and swerving across the screen in a 
cacophony of screeches, sizzles, and howling sound ef- 
fects. If a bomb penetrates and hits a city, the target is 
cleanly destroyed. Should a bomb hit a missile base, you 
lose it and any missile firepower that may have remained 
there. 

When the waves end, the computer tabulates your 
score, awards bonus cities for every increment of 10,000 
points, and then restores your three fully loaded missile 



bases for the next round. While the scores achieved with 
this game are lower than those of the arcade version, the 
scoring system and pattern were judged to be similar, and 
our panel generally felt comfortable at the controls. 

If you run out of missiles, the enemy becomes merciless 
and usually decimates what is left of your cities. Our 
judges disliked this tendency and claimed that the ori- 
ginal Atari version generally has enough built-in mercy 
to leave at least one of your cities when it finds you 
totally defenseless. Several times, the intelligence behind 
Missile Defense stunted the spirit of a good game by mer- 
cilessly obliterating three or more cities after we depleted 
our missile supply in the third or fourth round. 

ABM has a slightly different scenario. Here you defend 
the Eastern Seaboard, with its six familiar cities: Boston, 
New York, Philadelphia, Baltimore, Washington, and 
Richmond. You have both high- and low-yield defensive 
missiles, fired from five separate bases between the cities. 
You can choose to fire high- or low-yield, but the com- 
puter decides which base actually launches the missile. 
You have an unlimited number of defensive missiles to 
fire. Enemy weaponry includes single bombs and MIRVs, 
but no smart bombs. 

The attacks come continuously, at progressively faster 
and overwhelming rates. ABM gives a continuous read- 
out of your total shots and hits, but the final score only 
appears after all your cities have been eliminated. Scoring 
is low, with a record high of 7120. No matter how well 
you do, the computer never restores a single city during 
the game. There is no pause and no restoration of arma- 
ment until the game concludes. Judges preferred the ar- 
cade system, which pauses, scores, and restores cities 
before resuming the game. 



84 December 1981 © BYTE Publications Inc 



Circle 249 on inquiry card. 



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If a bomb penetrates your defenses in ABM, it fireballs 
on or near the ground, destroying everything within the 
fireball. This lends a swiss-cheese effect to your cities and 
allows you to lose half of Richmond or nine-tenths of 
Boston, for example — an impossible occurrence in the 
original version. If a missile base is bombed, you lose that 
firepower, although one active base is as effective as five. 

ABM has a special demonstration mode. If you boot 
the game disk and do nothing, it pauses, then begins 
playing itself. This is a fun introduction to the game, but 
has little relevartce to the quality of play and was prob- 
ably included as a marketing device. Touch any key and 
ABM goes into normal play. 

Both games keep your eyes, ears, and hands busy. But 
overall, our judges like the arcade version the best; more 
on this a little later. For now, let us examine the action 
piece by piece. 



Mobility 

Mobility is the prime factor in a high-scoring defensive 
system. The faster you can move your cross hairs to re- 
target your missiles, the better chance you have to repel 
the enemy attack and the more missiles you can fire if 
your first shots miss. 

The original game offers a special "rolling ball" (track 
ball) control to provide exceptionally fast mobility, 
which neither home game can match. Our test Apple is 
equipped with the standard paddle controls and, after 
some practice, our panel of experts was able to move the 
cross hairs about the playing screen with speed and accu- 




racy. The paddle controls, however, require a large range 
of motion to go from, say, upper left to lower right on the 
screen. Even the ABM adjustment program (more on this 
later) could not reduce the range of motion enough to in* 
crease overall mobility. This paddle problem affected the 
play in both versions of the game. Almost all the judges 
guessed that joystick controls on the Apple would make 
both versions of the game even better. 

ABM provides a blinking set of cross hairs that disap- 
pear for a short time immediately after you fire a missile. 
The launched missile heads for the spot your cross hairs 
occupied when you hit the firing button, but the cross 
hairs turn invisible. You can still move them, but you do 
not know where they are. This limits your ability to 
launch a rapid-fire counterattack. Even worse, it actually 
confused some of our panel. Habitues of the game invari- 
ably want to fire and retarget in almost the same motion. 
In that second or two of invisibility, the players lost track 
of the cross hairs and lost more time looking for them 
when they reappeared. With a joystick, there would have 
been better feedback from the fingers to help retain a 
sense of screen location. But the eyes have it in this game, 
and cross hairs that disappear are a serious liability — par- 
ticularly when the pace accelerates. In addition, the 
judges felt the blinking cross hairs were harder to see than 
the steady ones you get in the original version. 

Missile Defense offers a very stable cross-hair pattern, 
which remains visible throughout the game. Our judges 
found it simple to fire and instantly retarget for the next 
incoming object with this version. As with ABM, the mis- 
sile streaks toward the point where your cross hairs were 



A* a Glance 


Name 


Language 


ABM 


Applesoft and 6502 machine 




language 


Type 




Arcade-style game 


Computer 




Apple II or Apple II Plus, 


Manufacturer 


with Applesoft in ROM or 


Muse Software 


Language Card, 32 K bytes 


330 N Charles St 


of memory, and one disk 


Baltimore MD 21201 


drive 


(301) 659-7212 






Documentation 


Price 


Printed" leaflet 


$24.95 






Audience 


Author 


Anyone who likes fast- 


Silas Warner 


action arcade games, 




especially Atari's Missile 


Format 


Command 


5Vi-inch floppy disk 





_ ,Ata nianrp 


Name 


Language 


Missile Defense 


6502 machine language 


Type 


Computer 


Arcade-style game 


Apple II or Apple II Plus, 




with 48 K bytes of memory 


Manufacturer 


and one disk drive 


On-Line Systems 




36575 Mudge Ranch Rd 




Coarsegold CA 93614 


Documentation 


(209) 683-6858 


2-page leaflet 


Price 


Audience 


$29.95 


Anyone who likes fast- 




action arcade games, 


Author 


especially Atari's Missile 


Dave Clark 


Command 


Format 




5Vi-inch floppy disk 





86 December 1981 © BYTE Publications Inc 



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Circle 127 on inquiry card. 



BYTE December 1981 87 




when you fired. Meanwhile, you can be halfway across 
the sky, preparing for the next defensive shot. 

ABM offers a unique adjustment program so you can 
set up the paddles (or joystick) to suit your muscular in- 
stincts. Our judges applauded this ingenious feature and 
used it to make each paddle control react as they wished. 
This way, you can change the way the cross hairs re- 
spond to a given paddle movement if it seems wrong. 

Missile Defense offers the option of controlling the 
cross hairs from the paddles or from the keyboard. The 
U-I-0-L-.-,-M-J pattern of keys triggers movement in 
eight directions, providing a kind of "keyboard joystick." 
The more often you hit one of these keys, the faster the 
cross hairs move in the specified direction. A touch of the 
K key immediately stops the cross hairs. Some of our 
judges preferred this arrangement to the paddle con- 
trols, claiming it offers a closer simulation to the original 
track ball and that it facilitates one-hand operation of the 
cross hairs — a definite advantage in Missile Defense, as 
we shall discuss. 



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Defensive Missiles 

ABM provides an unlimited defensive arsenal. You can 
fire for an eternity, and ABM will remain poised to pump 
out more missiles on your command. (The original ver- 
sion strictly limits your firepower.) In ABM, you fire the 
missiles with the two paddle control buttons. One button 
fires missiles from the two bases equipped with 5-kiloton 
warheads; the other button fires missiles from three other 
bases, which are equipped with relatively tame 1-kiloton 
warheads. The adjustment program lets you decide 
which finger will deal each blow. The larger warheads 
create larger fireballs than their smaller cousins and, 
therefore, have the potential to engulf more incoming ob- 
jects. 

Despite the impressive fireballs, the need for accuracy 
is far greater with ABM than with the original. Some in- 
coming missiles seem to outrun the expanding fireballs, 
while others survive what looks like a solid hit. In the 
original, you can detonate your missile in the track of the 
oncoming enemy. The explosion lingers long enough to 
erase the intruder. With ABM, you cannot "lead" the tar- 
get very much, and hitting behind the attacker is usually 
ineffective. 

Missile Defense limits your defensive arsenal. Your 
missiles are released from one of three pyramids on the 
ground. Each time you shoot, the pyramid shrinks. When 
it disappears, that base is without missiles. Most of our 
players saw this as more comparable to the original ver- 
sion and a feature that adds an extra degree of challenge 
to the play. 

Missile Defense also plays more like the original in its 
accuracy and firing pattern. This game fires its missile 
from the keyboard. Pressing the 1, 2, or 3 key fires a mis- 
sile from bases on the left, middle, or right of the screen. 
While this is a sure and accurate means of directing your 
defensive fire, it requires three hands (when using two 
paddle controls) for rapid action. None of our judges was 
able to manipulate both paddles and the missile-firing 
keys conveniently with only two hands. However, all 
felt that the game played with the missile-firing keys is 
close to the original version. And, it must be admitted, a 
joystick — which could be operated with one hand — 
would eliminate any problem along these lines. 

Missile Defense has only one size warhead. But, again, 
this closely approximates the kill range of the original 
version's warheads. You can also 'lay down a pattern" of 
explosions with this game and watch the enemy drive 
into it. The explosive dust clouds linger long enough to 
trap an oncoming projectile and take it out. This is 
another factor that helps Missile Defense play very much 
like the original. 



88 December 1981 © BYTE Publications Inc 



Circle 370 on inquiry card. 



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Sound Effects 

Both games have some interesting sound effects. ABM 
provides a juicy sizzle when a missile or a bomb 
detonates. Missile Defense emits a tinkling sound when a 
missile or a bomb discharges. You also receive introduc- 
tory effects, a long, falling whistle when you lose, and 
finally, a flashing red screen (duplicating the ending of 
the original Atari game). 

Neither game produces the shooting sounds you get 
when you loose your own missiles in the original, and afi- 
cionados of the game claimed to miss the extra sound. I 
found both games noisy, active, and more than enough 
to occupy the senses. 

Graphics 

ABM provides an interesting display of the six East 
Coast cities. The colorful missile tracks break up and 
jump as they cross resolution lines on the TV screen, and 
the fireballs are expanding white circles that engulf and 
eliminate everything in range. 

Missile Defense has a nameless row of cities, also seem- 
ingly identical. The missiles come in smoothly, with very 
little break-up of their tracks on the screen. Smart bombs 
are shown as small plus signs. Explosions are detailed 
clouds of colored dots that grow, freeze, and evaporate 
within a few seconds. 




Both games play in the Apple high-resolution graphics 
mode, with exciting opening sequences. Neither game 
matches the original; however, which uses different color 
combinations as the action gets more intense. All things 
considered, they play almost identically in terms of quali- 
ty, action, and color. 

You may be interested in our judges' ratings. On a scale 
of to 100 — with the original Missile Command as 100 — 
Missile Defense rated 85 and ABM rated 75. The 
relevance of these numbers is unclear, but remember you 
heard it here first. 

Conclusions 

Both games are exciting, demanding, frustrating, 
challenging, and great fun. The preference seems to de- 
pend on your playing history. If you have spent a lot of 
time on the arcade original, you will probably prefer 
Missile Defense. It looks, sounds, scores, and plays much 
more like the original than ABM. It is like bringing the ar- 
cade game into your own home. 

If, like me, you have no experience on the arcade 
original, you may appreciate ABM's subtle differences: 
the unlimited shooting, the identification of the cities, the 
high- and low-yield weaponry, the continuous perfor- 
mance readouts, and the paddle adjustment program. ■ 



Gorgon 



Peter V Callamaras 

25 C Scott Circle 

Bedford MA 01730 



"Blue Three to Blue Leader — We have them in sight." 

"Blue Leader to Blue Three — Watch out for Space 
Mines. " 

"Blue Three to Blue Leader — We got them! But there's 
more on the wa..." 

"Blue Two to Blue Leader — They got Blue Three. 
They're all over the place! They grabbed one of our peo- 
ple and are carrying him off— I'm starting my attack run 
and..." 

"Blue Leader to Blue Base — we lost two ships. I'm the 
only one left. I'm breaking off and will commence the at- 
tack from the opposite direction. " 

Suddenly there is a blinding flash of piercing white 
light and a voice breaks in: 

"Honey — do you realize it's almost three in the morn- 
ing? 



Time passes quickly when you're playing Gorgon, a 
new arcade-style space game from Sirius Software. This 
is one of the typical high-quality, highly graphic games 
we have come to expect from the Sirius/Nasir team. Rest 
assured that you Nasir Gebelli fans will not be disap- 
pointed by this one I 

The premise behind Gorgon is fairly simple — the earth 
has entered a time warp, and strange creatures called 
Gorgons appear at random to abduct helpless earthlings. 
You are a fighter pilot trying to blast the Gorgons with 
your laser cannon before the kidnappings occur. 

If you are too late, you can still shoot the Gorgon who 
is carrying off one of your people. But you must then 
catch the falling human and lower him safely to the 
earth's surface. Hitting the earthling with your cannon 
fire or allowing him to hit the ground costs you 50 points; 
saving a captured earthling gains you 100 points. 



90 December 1981 © BYTE Publication! Inc 





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2, 8" dual-sided, double-density floppy 

disks (2.4 MB) 

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Supports 4 dumb terminals 




1 Same features as T7000 Terminal 
Monochrome graphics — 400 x 300 
pixel resolution 

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■ Optional touch panel 



68000 Processor 

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Single-user intelligent terminal 




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Photo 1: The game Gorgon in progress. 



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Your Gorgon opponents come in four different forms, 
each worth different point totals. Only one type grabs 
people, but the others release space mines that destroy 
your fighter on contact. You get three fighters during a 
game. 

The display for Gorgon seems complex at first, but you 
soon become accustomed to it (see photo 1). The bottom 
four-fifths of the screen shows a. side view of the earth's 
surface, which features undulating terrain and an occa- 
sional human. Above this is a situational sensor view 
showing your position relative to any Gorgons. Thus, 
you can leave the immediate battle area and do a bit of 
reconnaissance. Later, you can reenter the battle zone 
from a more advantageous direction. Next to the sensor 
screen is a display of your remaining ships (upper right 
corner). Below the terrestrial view is information on re- 
maining fuel, present score, and high score. 

You don't expect this game to be too easy, and it isn't. 
The Gorgons materialize at random locations in the bat- 
tle area, and hesitation at shooting them presents several 
problems: 

• The Gorgons destroy your fighter if they make contact 
with your craft before you can blast them. 

• The different creatures release two kinds of space 
mines which destroy your ship on contact; you can't 
easily shoot them down, but they temporarily disappear 
if you outrun them for a certain distance. 

• The more time you take to destroy the Gorgons or 
mines, the more Gorgons appear — and you are rapidly 
overwhelmed and destroyed. 

Fuel depletion can be remedied by the option that 
allows you to refuel from an orbiting space station. You 
must maneuver past your sensor satellites, and your 
lasers are deactivated. (The rationale is that you can't 
destroy the satellites because they give you information 
on the Gorgons in the other half of the game.) If you 
should collide with one of your sensor satellites, your 
ship is destroyed. This feature actually gives you a game 
within a game. 

Action is controlled from the keyboard. The game can 
be played without paddles if none are available. The 
game requires coordinated use of both hands to pilot the 
fighter and fire the laser. 

For a change, the choice of keys and their locations 
doesn't lead to the fatigue and finger cramps experienced 
in some other games — notably, those programmed in 
Japan. The A and Z keys control the vertical fighter 
direction and velocity, while the left and right arrow keys 
control the horizontal direction and speed (hit a key and 
the ship points in that direction; hit the same key and the 
ship's speed increases). It takes time to become accus- 
tomed to using the keys continually to change direction 



94 December 1981 © BYTE Publications lnc 



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and speed. But it isn't distracting. The space bar fires the 
laser, so it doesn't matter if you are left- or right-handed. 
This key arrangement is very comfortable and gives you 
a place to rest your hands. 



Affl rjl^n^p 


Name of software 


Format 


Gorgon 


5-inch floppy disk 


Type 


Language 


Arcade-style game 


6502 machine language 


Manufacturer 


Computer 


Sirius Software Inc 


Apple II or Apple II Plus, 


2011 Arden Way #225A 


with one disk drive (13- or 


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Documentation 




One-page instruction sheet 


Author 




Nasir Gebelli 





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During play, there are options allowing you to pause 
during the action, restart the game, or decide whether 
you want the sound effects on or off. (If you find yourself 
still battling Gorgons late at night, the silence option will 
really be appreciated!) 

Although Gorgon seems difficult at first, there's a com- 
pulsion to keep going (not the least of which is your 
gradually increasing score). The psychological factors 
that separate a good game from a mediocre one have 
been successfully incorporated in Gorgon. This isn't an 
easy game, but it's not difficult to start attaining better 
scores. The more you play it, the better you like it. You 
find yourself trying different strategies and discovering 
the intricacy of such games. You can simply wait and 
shoot the Gorgons as they appear, but then they get be- 
hind you — so you keep moving. Then you try running 
from the mines which suddenly surround you. Before 
you know it, another fighter bites the cosmic dustl I leave 
devising the "best" strategy — if there is one — to you. 

The graphics match what we expect from the Sirius/ 
Nasir team. The exploding fighters and laser fire are fan- 
tastic. When you finally get past the sensors and dock for 
fuel, you are rewarded with one of the best high- 
resolution graphics displays in the game I All movement 
in the game is smooth, and the playing pace never slows. 
Although the game is quite playable with either a black- 
and-white or color television set, color is the better 
choice. 

After your three ships have been destroyed, the game 
automatically reloads from disk (an unusual and frustrat- 
ing feature for an Apple game). Since the game retains 
your highest score, you always have a new goal to ex- 
ceed. You can still play the game in the demonstration 
mode, albeit with only one fighter. 

If you are inclined to visit the local arcade to compare 
Gorgon and its counterpart (Williams' coin-operated 
"Defender" game), I think you'll agree Gorgon is more 
easily assimilated. Your scores climb faster, and the game 
is just more fun to play. This is a welcome change from 
home computer games that come close to the arcade ver- 
sion, only to leave you tossing away quarters to play "the 
real thing." 

Conclusions 

At first, I expected to find Gorgon just another arcade 
game converted for the Apple. But it's well programmed 
and much more enjoyable than the arcade version. The 
initial difficulty of getting used to the keyboard action 
vanishes very quickly. (All too often, I find a good game 
that requires too much time to get comfortable with the 
action or to get a reasonable score. I soon lose interest 
and regret having bought the game in the first place. You 
won't have that problem with Gorgon.) 



98 December 1981 © BYTE Publications Inc 



Circle 196 on inquiry card. 



A Database System 

so sophisticated 

a beginner can use it. 

This didn't come easy. To bring it off, a join, they just create a new table. Soon 

we had to invent the first-ever combined these additional tables clutter up the disk 

relational database system and word storage with redundant information, 

processor. If you edit a join, all you'll correct is that 

The result was Sequitur. It's amazingly one joined table, not the tables the data 

easy to talk to, because it does some things came from, 
you only find in systems that cost ten times On the other hand, Sequitur 

as much and a few things you can't find in displays joined tables, but it doesn't store 

any other system at all. them. So when you edit, the edit goes 



It's smart enough to be friendly. 

Because Sequitur is a word processor, 
it gets by with a minimum of artificial 
codes. When the beginner enters, 
edits, excerpts or reports, Sequitur 
helps, step by step. That same 
helpful nature shows up when 
a computer expert uses 
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You and Sequitur organize 
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To add an entry, just fill in 
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The wonders of the 

Integrated Edit. 

The beauty of a relational 
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back to the base table automatically, 
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— This edit won't destroy what went 

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It has a beginner's price. 

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Pacific Software Manufacturing Company 




The Gorgons come faster as your score rises, until 
destruction is imminent. If you play Gorgon long 
enough, however, you may discover a little quirk in the 
program which allows you to take over control of the 
game and defeat the Gorgons. (I'll let you find that your- 
self.) 

Refueling takes you into the second portion of the 
game, which is perhaps as challenging as trying to shoot 
Gorgons. Though you quickly ascertain how to 
maneuver past the sensor satellites, you find yourself get- 
ting fancy and, after losing several fighters, you revert to 
zapping the Gorgons. 

Sirius was correct in making Gorgon a keyboard-con- 
trolled game. You aren't faced with the necessity of a joy- 



stick or controllers, but can begin play at once. This 
game may even help develop hand-eye coordination in 
youngsters or physically handicapped players. 

Although Sirius uses only premium disks, you can get 
a replacement for a flat $10 fee. This should relieve those 
worried about wearing out the disk through the constant 
reloading of the game. 

The documentation is adequate and the overall quality 
of the game is very high, in programming and payabili- 
ty. Since Sirius doesn't sell its products directly, you may 
have to get in line at your favorite dealer or send off an 
early mail order. A good model for you future game pro- 
grammers to follow, Gorgon should provide many hours 
of enjoyment. ■ 



Commbat: A Tele-Game for Two 



George Stewart 
Technical Editor 



Most computer games are solitary activities. Whether 
you're hunting Klingons, exploring an imaginary world, 
or racing down an endless loop, it's you versus the com- 
puter. That relationship can become a little dry; after all, 
what does a computer know about the thrill of victory or 
the agony of defeat? 

Commbat, a war game from Adventure International, 
offers a novel and exciting alternative to one-player 
games. It's a "tele-game " which you and a friend play 
using two computers linked by phone lines. The contest is 
one of strategy, tactics, and reflexes. Most important, 
your opponent is a human, not a computer; the com- 
puters serve merely to create an imaginary battlefield and 
to function as combat consoles. 



The Scenario 

You and your opponent have been commissioned to 
engage in single combat; the outcome will resolve a 
dispute over mining rights to uranium deposits on a 
planet in the Deneb galaxy. (It could just as well have 
been oil in the Middle East, but that wouldn't have of- 
fered as much escapist fantasy.) The battle area is 
vast — 4096 square kilometers. Each of you has a base sta- 
tion and a military arsenal of eight tanks, four recon- 
naissance drones, three decoy bases, 200 mines, 250 
shells, 255 laser units, 200 rockets, and one ICBM. 

To win Commbat, you must destroy your opponent's 



base, and that's no easy task. When the game begins, you 
select your base's position and your opponent selects his. 
Neither of you has any idea where the other's base is. 
Using tanks and reconnaissance drones, you've got to 
pinpoint the enemy base. The problem is that you can't 
easily distinguish decoys from the real thing; it takes 
careful observation and deductive reasoning to make the 
determination. The only practical way to destroy the 
enemy base is with your single ICBM. If you waste the 
missile on a decoy, your game prospects are grim. 

While you're out searching for the enemy base, your 
opponent is doing likewise. This means you must take 
defensive measures, too — like laying mines, setting up 
decoys, and positioning tanks at strategic points 
throughout the battle area. All of these objectives become 
immediate goals; destroying the opponent's base becomes 
a distant, ultimate goal. As in real war, there are many 
minor victories and losses in the field as your tanks 
destroy and are destroyed. A game may last anywhere 
from 30 minutes to four hours. 

How Good Is It? 

The key to an enjoyable, interactive strategy game is 
having "tools" that work convincingly in the imaginary 
world. The more complex the tools and the more intricate 
the natural laws of the imaginary world, the better. By 
this criterion, Commbat is a great success. Although it 
takes a while to use them proficiently, the tools 



100 



December 1981 © BYTE Publications Inc 



SUPERVYZ-THE NEXT INDUSTRY STANDARD 



SUPERVYZ is a revolutionary 
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ACT • SEC (SID 



TANK 2 5 26,11 
2 BECY 1 5 19, 8 
BASE 1 8 16, 8 

TANK CAP 4188 

base m becoy 

~ SHIEU 168 8 8 

+ HINES 177 8 8 

♦B+ ROCKET 288 8 8 

♦ + BULLS 247 @ e 

+ USER £85 39 8 

DECOY 1 MW 4 



COHHAHD OBJECT IFIRE CON 
(S)ELECT (DANK 8 1 2 

<D)ROP (S)ECOY 7 I 3 

(L)OflS <B)flSE 6 5 4 

WIRE (H)INE XFIRE CON 
OOELP (R)OCXETI S X V 
OOAP (S)HELL X SVNBOLS 
(:> HS6 (L)ftSER I B BASE 
WATCH (A)IRRCX D DECOY 
(UU1T (I)CBN X I ENN T 
(OASSETTE SAVE N OK T„ 

SMfu cohhands torn Hi 

FIRE SHELL 1 22 18 x MM T. 
HSE LASER 6 I BOUNDAR 

HOP HINES 3 LOAD SHELL (1) 
WTCH 2 4 5 SELECT TANK 2 



CHD?_ 

SANE OR PRACTICE SESSION <«/P> 



a 



ACT I SEC 6RD 



I TANK 8 e 8 8 
JECT 8 8 8 8 
BASE 8 8 8 8 
TANK CAP 
BASE TAW BECOT 

SHIELD 188 

I HINES 288 
ROCKET 288 
SHELLS 258 
LASER 255 
— DECOY 8 BROKE • 



Photo 1: The Commbat console display in the heat of battle. 
The left side of the screen is a map of sector 5, according to the 
base computer's latest information. The "X" represents an 
exploded tank; "2" is your own tank; "D" is your own decoy; 
and the "+"s are your mines. In the upper right portion of the 
screen is a message you are about to send to your opponent. The 
three rectangles in the center of the screen are windows on your 
decoy, tank, and base. 



Photo 2: The Commbat console, showing the command and 
function summary available through the "help" command. 



(weapons, in this case) are impressive from the start. 
And although the terrain is too vast to display on the 
screen at once, it doesn't take long for you to form a men- 
tal map and to begin thinking of a real space somewhere 
beyond the confines of the combat console. In short, the 
game is credible. 

Take the console display for example (see photo 1). It 
has six components: 

• a map display showing the latest information about any 
of the 16 by 32 kilometer sectors (as sensed by one of 
your tanks or drones) 

• three windows displaying the immediate areas around 
your base, one of your decoys, and one of your tanks 

• status indicators reporting on the location and condi- 
tion of your base station and all tanks and decoys 

• a command line, where your typed commands are 
displayed, along with urgent reports from the field and 
messages from your opponent. 

Suppose you have a tank and a decoy in the same 7 by 
7 kilometer area. Looking out the tank window, you see 
the tank (designated by a "T") in the center and a decoy 
("D") off to the left. But looking out the decoy window 
gives the opposite picture, with the decoy in the center 
and the tank to the right. Move the tank one space to the 



left. In the tank window, the tank remains sta- 
tionary — since it is the reference point — and the decoy 
appears to move toward the tank. But in the decoy win- 
dow, the opposite takes place: the decoy remains in the 
center and the tank moves toward it. Motion is relative to 
the observation point. It takes some getting used to on 
your part, but this consistent modeling is what makes 
Commbat so intriguing. 

Using Commbat is definitely a learning experience. 
When you first start playing, you'll probably employ just 
the simplest tools. As you progress, you'll begin to 
appreciate the advanced capabilities. For example, using 
the "patch" command, you can advance two or more of 
your tanks and fire weapons in unison — creating a 
massive onslaught on your enemy's defense lines. 

Another essential game element is its interactiveness. 
You and your opponent can move, fire weapons, and 
select different tanks and decoys at any time. This makes 
the game infinitely more challenging than the typical, 
wait-your-turn war game played on a board. Suppose, 
for example, that while you're typing in a command, you 
notice some enemy action through one of your three win- 
dows. You can cancel the command and make an 
immediate response to your opponent. You can even 
send him a message at any time ("Let's quit for a while," 
"Aha!" or some distracting thought). 



102 December 1981 © BYTE Publications Inc 



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Playing the Game 

A typical game session goes like this. You telephone a 
friend who also has the Commbat program. The two of 
you agree on what RS-232C characteristics you'll use and 
set up your Model I or III TRS-80s accordingly: word 
length, parity, number of stop bits, and bits per second 
(this last is set whenever you start the program). 

Each of you starts the Commbat program, maintaining 
voice contact over the phone lines. Commbat will ask 
you for some start-up information, including what 
transmission rate you want to use. With most modems, 
you'll be limited to 300 bits per second. Finally, the com- 
puter will tell you to press the Enter key to check the 
communications link. Both of you must do this at ap- 
proximately the same time and immediately put the two 
computers on line. When the computers are synchro- 
nized, you will be asked to select your base location. 
Then the actual combat begins. 

Special Features 

Commbat has several important convenience features. 
For example, there's a practice mode to get you ac- 
customed to moving your tanks around, deploying mines 
and decoys, and even firing weapons (if you don't mind 
destroying your own resources). You don't have to be on 
line with another computer to use the practice mode. 

Another important feature is the ability to save games 
on tape or disk for later retrieval. You'll invest a lot of 
time and thought in some Commbat games; the ability to 
save a game precludes the need to throw it away if the 





Name 


Format 


Commbat 


Cassette "system" file 




Mini-disk "command" file 


Type 




Two-player strategy game 


Language 


using telecommunications 


Z80 machine code 


Manufacturer 


Computer 


Adventure International, a 


Radio Shack Model I or III, 


Division of Scott Adams Inc 


with at least 16 K bytes 


POB 3435 


(cassette version), or at least 


Longwood FL 32750 


32 K bytes and one disk 


(800) 327-7172 (phone orders 


drive (disk version); RS- 


only) 


232C interface and modem 


Price 


Documentation 


Cassette version, $19.95 


12-page leaflet, plus com- 


Mini-disk version, $20.95 


mand and function summary 




available in program 


Author 




Bob Schilling 





session is interrupted. To save a game, both combatants 
must enter secret passwords. For either to load the saved 
game, both of them must enter their passwords. This 
prevents either player from cheating by improving his 
position in the other's absence. 

Documentation 

Commbat's manual is adequate. Most useful is a one- 
page reference sheet. In addition, the program offers a 
"help" command, which displays a command and func- 
tion summary at any time (see photo 2). 

Suggestions for Improvement 

I found Commbat's main fault not in the game itself, 
but in the procedure required for starting it. Both players 
must start the "check-commlink" sequence almost 
simultaneously; otherwise, the program will "hang up," 
and you'll both have to reset your computers. This pro- 
cedure can be a little tricky if you're using a single 
telephone and an acoustic modem. Ideally, it wouldn't 
matter when you started the check-commlink se- 
quence — the first computer would simply wait until the 
second computer came on line. A programmer at Adven- 
ture International acknowledged that the present method 
is a little awkward, but said that the program's author 
has yet to find a good solution. 

Another complaint is that the keyboard response occa- 
sionally seems sluggish: you'll type in a command and 
press Enter, only to realize that one or more of your 
keystrokes were missed. Of course, this always seems to 
happen at the worst times, as when you're engaged in 
battle with an enemy tank. The Adventure International 
programmer pointed out that this keyboard-response 
slowdown is an unavoidable limitation of the system due 
to the great amount of data being sent back and forth 
across the phone lines. (Both computers must keep com- 
plete data on both players, even though each player gets 
a much more one-sided view of things.) 

The keyboard sluggishness isn't all that serious. For 
one thing, it's experienced by both players and won't 
give either an advantage. As well, it's not hard to accept; 
after a while, you begin imagining that your weaponry is 
becoming rusty or intermittent due to the stress of battle. 
Carry on! 

Conclusions 

Commbat opens an exciting new realm of multiplayer 
computer games in which the players may be anywhere 
that phones are available. Shedding their role as im- 
passive opponents, the computers become active tools for 
competition between humans. 

The imaginary world of Commbat is interesting and in- 
tricate, and it really does test one's strategy, tactics, and 
reflexes. ■ 



104 December 1981 © BYTE Publications Inc 



C-inn crura- mcmhou pocoi^ruoni iru 
_/ iuu -m iiil i (Li iui 1 1 ui ili inn ii iuuui i 



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32K RAM by Microtek 189 

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Parallel by CCS #7720A 99 

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APPLE ACCESSORIES 



Adventure by Microsoft 27 

Alien Rain by Broderbund 19 

Apple Pie by Programma 119 

Apple-Oids by CPC 25 

Apple Panic by Broderbund 24 

Asteroid Field by Cavalier 19 

Basic Compiler by Microsoft 349 

Business Pkgs. by Continental 199 

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Joystick 47 

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TO ORDER: Mail orders may send cashier check, money order or personal 
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or Purchase Orders accepted. Include 4% for UPS shipping, handling and 
insurance. Shipments to CA address must also include 6% sales tax. Please 
include phone number on all orders. RUSH ORDERS AVAILABLE using 



Visa or Mastercard (subject to credit card approval from our authorization 
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(714) 579-0330 • MAIL TO: 1251 BROADWAY, EL CAJON, CA. 92021 




aix§aimMS 



DIV OF 

COMPUTER 

METRICS 

INC 



Circle 91 on inquiry card. 



Hardware Review 



alphaSyntauri Music Synthesizer 



Steve Levine and Bill Mauchly 

c/o Audio Data Consultants 

POB 224 

Ambler PA 19002 



Music and computers seem to go together naturally. 
Indeed, there appears to be some metaphysical link be- 
tween them. Musical minds take readily to programming 
concepts, and it's hard to find a coven of computer pro- 
grammers without at least one musician in its ranks. The 
idea of making music with computers is almost as old as 
the computer itself. 

But the human interface is always a problem. How do 
you translate the idea of making music into a computer 
program? 

A musical score is much like a program; it's a list of in- 
structions with various branches and repeats. So the ob- 
vious solution is to give the musician a language to 
describe the music. This may then be fed into the com- 
puter for the result. Until recently, using slow, batch- 
mode processing could mean waiting a day or more for 
the sound to reach your ears. Even worse, the computer 
needed to know exactly what was desired. But how was 
the poor musician to know in advance what he wanted to 
hear7 He's heard violins before, but what does a com- 
puter sound like? 

The dawn of the microcomputer promised a new era in 
computer music. Suddenly, the machine was yours alone 
and when you said RUN, it ran. But both the hardware 
and software of the first microcomputer music systems 
ignored the need for real-time feedback. Maybe the soft- 
ware allowed the score to be typed into a screen editor 



About the Authors 

Steve Levine is a microprocessor engineer whose interest in 
computer music has run the gamut from controlling pipe organs 
to digital signal processing. He has coproduced the unique Com- 
puter Music Festivals in Philadelphia for four years. Bill 
Mauchly is a recording engineer and musician. Son of the 
father-of-the-computer, John W Mauchly, his knowledge of 
computers is genetic. Levine and Mauchly formed Audio Data 
Consultants in 1980 to collaborate on ideas in digital synthesis 
and signal processing. Research with the Fairlight CMI, coupled 
with the production of the Symposium of Small Computers in 
the Arts this November, has brought them in close communica- 
tion with many computer musicians. 



rather than with a keypunch, but it still made you wait 
until the computer was ready to play the music. 

The Syntauri Corporation has changed all that. A five- 
octave music keyboard and a disk of software form the 
heart of the alphaSyntauri synthesizer. The software 
allows control of the sophisticated Mountain Computer 
MusicSystem digital synthesizer hardware from the 
keyboard, via an Apple II computer. (See "Mountain 
Computer's MusicSystem," July 1981 BYTE, page 60.) 
The alphaSyntauri system allows music to be played 
directly or to be recorded and played back. It allows the 
changing, storing, and recalling of waveforms, 
envelopes, and tunings. Most important, because it is 
based on the Apple II computer, it is possible to change 
or add to the system software. 

User interaction, which is the primary advantage of 
microcomputer systems, has been extended to play — not 
just write — music. Immediate feedback links the creation 
to the sensation of music. For the first time, the personal 
computer is an instrument, not a glorified music box. 

This article reviews the capabilities of the alphaSyn- 
tauri synthesizer as a musical instrument and discusses 
the hardware and software details of interest to both 
musicians and computerists. 

The Syntauri Philosophy 

The alphaSyntauri music synthesizer is a software- 
based system and the brainchild of Charlie Kellner. Aside 
from the Mountain Computer synthesizer boards, the 
system uses an interface card and a professional music 
keyboard. But the system is more than just an Apple 
peripheral; it is a musical instrument in its own right. Its 
price and performance clearly place it beside commercial 
synthesizers made by Moog, Oberheim, Arp, Yamaha, 
and Sequential Circuits. Its modular design with software 
flexibility makes it comparable to such digital syn- 
thesizers in the $20,000-$30,000 bracket as the Synclavier 
II and the Fairlight Computer Music Instrument. Ob- 
viously, these more expensive synthesizers can produce 
sounds with higher quality than the alphaSyntauri music 



108 December 1981 © BYTE Publications Inc 



tOmPUTER WAREHOUSE 



CALL TOLL FREE 



ATARI 

Special 32K 800 System 

800 w/32K, recorder, star 

raiders, joysticks $900 

Above w/48K $960 

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32K Memory $150 

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ALPHASYNTAUR1 
KEYBOARD 




VIDEO 
DISPLAY 



APPLE H 
COMPUTER 



CZJ 



APPLE 
DISK DRIVES 



Figure 1: This shows the hardware con- 
figuration and the interaction of the 
various system parts. 



I 



OSCILLATOR 
HARDWARE 




SPEAKERS 





























































• AUDIO 
OUTPUT 




KEYBOARD 


KEYBOARD 


PADDLES 


SYNTHESIZER 












REAL Tl 


VIE 
















n 














1 


il ii 














ALPHAPLUS 
MAIN PROGAM 














DISK ST 








i 


i 


i 


, 




' 


i 

r 


i i 


i 


- 






3RAGE 








1 
















' 




















WAVEFORMS 




PRESETS 




NOTES 




TABLES: 

SCALE 

VELOCITY 

AMPLITUDE 




FX 

SUBROUTINES 






1 




1 








i, 




















* 








' 
















t 




J_ 












ANALYZER 


m 




WAVE TH 
(SYNTHESIS) 




SEQUENCER 




VELOCITY 




LOG HI 




SCALE m 



AUXILIARY PROGRAMS 



Figure 2: The ALPHAPLUS program is the main program, with auxiliary programs providing or modifying data for ALPHAPLUS. 



synthesizer. But even these "super-synthesizers" do not 
allow prying into the operating system. Unique in a 
world of black boxes, the alphaSyntauri synthesizer is a 
music system that a user may customize. 

The advantage of software functions over hard-wired 
features is that they are so easily changed. First, the 
manufacturer can provide updates as new features are 
developed; planned obsolescence is replaced with upward 
expandability. Second, the infernal musician, notorious 
for making his tools do things "they weren't meant to 
do," has a truly programmable instrument. The 
alphaSyntauri synthesizer is ideally suited to those stub- 
born types who aren't always satisfied with the 12-tone 
scale, who insist on using the Dow-Jones average as a 
waveform, or who would like to jam against a sequence 
of notes resembling the Maine coastline played in three- 
quarter time. Programmability is the single most impor- 



tant advantage of the alphaSyntauri system over all other 
keyboard synthesizers. 

Turn It On 

The alphaSyntauri disk boots itself up, asks you if 
everything is plugged in the same as it was yesterday, and 
brings the synthesizer up with a group of 10 preset 
sounds. Presets on the alphaSyntauri synthesizer are 
preprogrammed instruments or sounds, similar in con- 
cept to organ presets. Only one is active at a time, and 
pressing the number keys (0-9) on the Apple allows selec- 
tion of different presets. 

The preset's name is shown on the screen, along with 
the envelope parameters which describe its dynamics. 
The music keyboard is then instantly alive with the sound 
of vibes, clavinet, clarinet, B3 organ, pickle, bump, or 
whatever you have selected. Push another number, and 



110 December 1981 © BYTE Publications Inc 



Circle 194 on inquiry card. 



TIK 




unycncT ws™ 



ITS FEATURES POINT TO YOUR SUCCESS 



128 K 9 Bit Parity 
Checking RAM 



Software Selectable 
Baud Rates 



Programmable 
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2 Independent 
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Full Synchronous or 
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Fully Socketed IC's 
For Reliability 



Parity LED 



Card Ejectors 




Software Selectable 
Bank Switch Boundary 

4MHzZ-80ACPU 



2 K or 4 K 
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IEEES-100 



Switch Selectable 
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Full S-100 interrupts 



Onboard programmable 
Interrupt Control 






Reliable 2 Sided PC Board 
With Gold Plated Contacts 



AMD 9511 or 9512 
Hardware Floating Point 

The IBS SLAVENET 128 is a totally independent and complete computer capable of supporting 
two timeshared users. The SLAVENET 128 communicates with your own CPU as an I/O mapped 
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IBS is a trademark of IBS, Inc. 




Photo 1: The Envelope Control Screen is shown with a color 
display of a C major chord. PDO and PD1 are live paddle 
displays of the vibrato and FX controls. 



Photo 2: WAVE III Additive Synthesis Wave Creation Pro- 
gram. When the program first comes up, it displays each of the 
stock waveforms available and, as they are plotted, the cor- 
responding sound is heard from the amplifier. 



you get another sound. Simplicity and speed make the 
system easy to learn and elegant to use. For added 
wonderment, a 12-color graphics display dances across 
the video screen, following the notes of the keyboard. 

Software 

The alphaSyntauri software has one main program 



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that provides the personality of the keyboard in- 
strument — plus a library of programs for configuring, 
analyzing, and generating control parameters which can 
be used by the program (see figure 2). The system we 
evaluated (a prerelease version of AlphaPlus) will have 
been released as an enhancement to Alpha III (the first 
software revision) by the time this article is printed. 

The main program becomes the synthesizer's "control 
panel," with screen displays for parameters entered with 
the Apple's alphanumeric keys. Pressing an "A", for ex- 
ample, makes the cursor jump to a field at the bottom of 
the screen, where AR = 210 might be displayed. This is 
the Attack Rate, or the speed at which one of the 
envelopes will rise to its maximum value every time a key 
is depressed. The value may then be altered, either step- 
wise using the left or right arrow keys, or by typing a 
number and hitting return. The result is similar to ad- 
justing an array of knobs; it's a little slow, but more ac- 
curate. From this control panel, all of the real-time func- 
tions — including music recording, playback, presets 
loading, and editing — may be accomplished with a few 
keypresses. 

The alphaSyntauri software controls the 16 oscillators 
of the Mountain Computer hardware by pairing two 
oscillators per voice to provide an eight-voice syn- 
thesizer. If all eight are already playing, then the first 
voice used is reassigned to the new note. Since all eight 
sound identical, it is impossible (and irrelevant) to tell 
which oscillator is assigned to which note. 

Both of the two oscillators per voice are available as 
separate outputs. Although this allows stereo effects, the 
correct use for most sound involves mixing together 
monophonically. The two oscillators use different wave- 
forms and different envelopes, but are activated 
simultaneously (see figure 3). This is essentially similar to 
two separate eight-voice synthesizers hooked to the same 
keyboard. 

One of the oscillators is designated the Primary, while 
the other is called the Percussive. These names are actual- 



112 December 1981 © BYTE Publications lnc 



Circle 69 on inquiry card. 



WHAT'S THE KEY 
TO BUYIHG A COMPUTER? 



Look beyond the computer. Look at how the total 
system- hardware, software, support, service- 
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Software 

Including word processing, business applications, 
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For your own custom programs, Microsoft languages 
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Friendly, experienced technicians are available, 
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Pick the store nearest you from the list on page 233. 
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Photo 3: This is the result of using the WAVE III program. This 
waveform shows the addition of the first, second, third, and 
fourth harmonic, with the respective amplitudes of 50, 40, 30, 
and 20 percent. 



ly arbitrary, for it is certainly possible to put a very per- 
cussive envelope on the primary oscillator. At any rate, 
the parameters describing the two currently active 
envelopes are displayed at the bottom of the screen, while 
a simple Control-W allows you to view the names of the 
waveforms loaded into the primary and percussive 
oscillators. Pressing the 7 gives a catalog of the disk so 
that you can see what waveforms are available. 

A number of useful waveforms come on the system 
disk. They include sine, triangle, square, and that old 
standby, sawtooth. Also, any arbitrary waveform may 
be created through additive synthesis, to be discussed 
later. 

The primary and percussive waves are offset in fre- 
quency by a user-defined amount of 16 semitones per 
note (ie.- 16 possible steps from C to C#). Selection of a 
great enough offset produces the effect of two notes per 
one keypress. A more practical use, however, is to slight- 
ly offset the two oscillator frequencies to add a fullness or 
fatter sound. This works especially well for synthesized 
piano or organ sounds. 

Envelopes 

The envelope controls (determining the rise, duration, 
and fall of each note) are straightforward and easy to use 
(see figure 4). They are laid out logically, and one or two 
keypresses will move the cursor to any parameter you 
wish to change. The letters A, D, and R, for example, 
select the Attack Rate, Decay Rate, and the Release Rate, 
respectively, for the primary wave. The letters P and F 
select Percussion Rate and Fall Rate, which are simply 
different names for the attack and release of the per- 
cussive envelope. One more key press will drop you 
down to the second line, where the levels are displayed. If 
you press P, for example, you select Percussion Rate; 
whether or not you change it, pressing Return will drop 
you to Percussion Volume. 

A few other parameters at the bottom line affect special 
envelope controls. The percussion channel of the instru- 




Photo 4: The ANALYZER III graphic display shows a rich pulse 
wave which was synthesized with another program, AUTO- 
PULSE, written by Steve Leonard. ANALYZER III is shown 
performing an analysis on the wave, with a numerical output 
for each of the harmonics and their respective amplitudes. 

ment can be turned off, leaving just the primary. This 
same parameter controls the velocity-sensitive envelope. 
When on, the velocity with which a key is struck will 
modulate the attack rate and volume (for the primary 
wave). The quicker the key goes down, the faster the 
attack rate. A very nice, expressive quality results once 
you get comfortable with this control. 

Another special feature in the envelope section lets you 
loop the primary wave envelope so that it is constantly 
executing its attack and release curves. The result is 
similar to tremolo; the amplitude is fluctuating 
periodically. The effect is useful for certain sounds, like 
putting the vibe in Vibraphone. 

The frequency control (FC) simply tunes both 
waveforms by quartertones in relation to some arbitrary 
zero point. 



Vibrato 

A last major control panel parameter is vibrato, which 
is a controlled modulation of the frequency. The Apple II 
game paddles are used to control the amount or "depth" 
of vibrato (PD1) and the speed of change or rate (PDO). 
The vibrato is extremely effective in giving a more 
realistic and dynamic sound to most instrument settings. 

Presets 

All of the parameters shown on the screen, together 
describing one preset, may be saved or recalled from 
disk. Although only one preset is active at any moment, 
10 different sounds are loaded in memory and ready to be 
selected. The entire configuration of 10 different presets 
may also be stored on disk as a Preset Master. A preset 
master has the advantage of storing the waveforms that 
were loaded into each preset. This creates a Waveform 
Master on the disk. (Ideally, individual instruments 
should also have an automatic waveform recall; but not 
in this version of the software. 

The preset master feature is very important in a perfor- 



114 December 1981 © BYTE Publications Inc 



APPLE • ALTOS • ATARI • MAXELL • DYSAN • EPSON • CCS • SHARP • CASIO • HP • VERBATIM • MEMOREX • SOROC • CORVUS • ADDS 



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MAXELL • DYSAN • EPSON • CCS » SHARP • CASIO • HP • VERBATIM • MEMOREX • SOROC • CORVUS • PERSONAL SOFTWARE • CCS 



Circle 251 on inquiry card. 



FROM 

SCALE TABLE 



FM 

(FREQUENCY MODULATION) 



FC 

(FREQUENCY CONTROL) 



1/2 Hz OFFSET 



PERCUSSION 
ENVELOPE 




INPUT FROM 
SEVEN OTHER 
PERCUSSION 
OSCILLATORS 




PRIMARY 
ENVELOPE 



"N 



INPUT FROM 
SEVEN OTHER 
PRIMARY 
OSCILLATORS 



STEREO OUTPUT 



Figure 3: The flow diagram is a model of the synthesis process for the development of 
computer-generated music. 



VOLUME 




KEY DOWN 



KEY UP 



Figure 4: This example shows the various parameters and their relationships, which 
determine the sound of a preset. The dual envelopes, produced when a key is pressed, 
control the amplitudes of the two oscillators. The parameters for the selected preset are 
displayed as integers from to 255 (255 being the fastest or loudest). When key velocity 
is fast, AR and AV are increased. When the sustain pedal is depressed, DR replaces RR. 



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116 



December 1981 © BYTE Publications Inc 




IFOR NEW USERS. 
CompuServe is in the holiday 
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Circle 79 on inquiry card. 



mance situation, where a particular song may call for five 
different sounds in quick succession. A preset master for 
that song might contain the required presets in numerical 
order. All the performer must worry about then is 1, 2, 3, 
not preset #42, #13, or tibia 16'. Incidentally, when a 
composition is recalled from disk (as will be described in 
the next section), it selects the numbered preset that was 
active when it was made. 

Recording Performances 

Like any good computer music system, the alphaSyn- 
tauri synthesizer simplifies recording key closures and 
their associated timing information. This is not unlike an 
analog synthesizer sequencer, except the music program- 
ming is accomplished by playing on the keyboard. Key 
velocity, pitch, and duration are saved in a memory buf- 
fer. Then, with the SAVE command, they are written to 
a disk file with the prefix Notes. With 48 K bytes of 
memory, you will be able to store up to 3285 note events. 

The sequence of keystrokes to initiate recording is very 



Ar a danrp 


Name 


Apple's DOS 3.3 


alphaSyntauri Music 




Synthesizer 


Computer 




Apple II or Apple 11+ with 


Type 


48 K bytes of programmable 


Sound development system 


memory, at least one disk 


for performing and 


drive, and Apple's DOS 3.3. 


recording 


Both Applesoft and Integer 




BASIC are required 


Manufacturer 




Syntauri Corporation 


Documentation 


3506 Waverley St 


Documentation includes a 


Palo Alto CA 94306 


tutorial manual, two quick 


(415) 494-1017 


reference guides, and a 




technical manual 


Price 




$1500 


Hardware Required 


. 


Mountain Computer 


Hardware 


(formerly Mountain Hard- 


An interface card occupies a 


ware) MusicSystem music 


slot in the Apple II. The 


synthesizer boards, a stereo 


professional music keyboard 


amplifier, and speakers are 


and foot pedals connect to 


required. (The operating 


the card 


system originally supplied 




with the Mountain Com- 


Software 


puter hardware is not used) 


An operating system is sup- 




plied on disk. Several pro^ 


Comments 


grams allow sounds and 


The alphaSyntauri system 


music to be developed, 


can also be configured for 


changed and recorded 


use with the ALF Music 




Synthesizer from ALF Pro- 


Language 


ducts Inc 


The programs are written in 




6502 assembly language, 


Audience 


Applesoft BASIC, and 


Apple II owners who want 


Integer BASIC. An assembly 


to compose music, create 


language listing is available 


sounds, or do live perfor- 


from Syntauri Corp 


mances 


Software Format 




The disk supplied requires 





simple. From the main menu, just press the space bar R 
for record (the remaining number of notes will be 
displayed on the screen) and then hit Return. This will 
return you to the main menu, where the instrument name 
will be in reverse video to indicate you are in the record 
mode. The program will wait for your first keystroke 
before starting to save the notes in memory. 

Once you finish the sequence, hit the space bar and 
then S (Save). You will then be asked to provide a file 
name for your performance. Hit Return for a saved per- 
formance. 

An interesting recording sequence feature is Echo. This 
allows instant, continuous playback of the last recorded 
sequence. Many musicians find this useful for accom- 
paniment purposes, though a perfectly spliced sequence 
is difficult to create. When you finish playing the seg- 
ment, hit the space bar and the sequence will play back 
with a rest inserted between the last and first notes 
played. This rest will equal the time between the last note 
played and the point at which you hit the space bar. For a 
good splice, it is necessary to hit the space bar just ahead 
of the next note's downbeat. 

The Mountain Computer synthesizer generates an in- 
terrupt every eight milliseconds. Syntauri's alphaPlus 
operating system uses every other interrupt for a watch- 
dog timer. This makes it easy to synchronize the key- 
board playback with another timebase for playing along 
with prerecorded music. Previous releases of the software 
did not use this timebase and suffered severe slowdown 
when the keyboard was used during playback. The inter- 
rupt system virtually eliminates the problem. In summa- 
tion, the sequencing ability of the alphaSyntauri syn- 
thesizer is a deluxe feature. 

Programmability 

To now, we have examined the way the system 
behaves as a conventional synthesizer, with functions 
that all operate in real time. If we drop out of the main 
program, however, we may run programs which can 
create, modify, or analyze data used by the system. This 
data is in binary disk files which contain tables or lists. 
These tables are used by the main program and include 
waveforms, notes, tunings, and functions for mapping 
velocity and amplitude values. The programs provided, 
and those created by the user to manipulate that data, 
provide the programmability that sets the alphaSyntauri 
system apart from all other synthesizers. Although de- 
tailed documentation on the architecture of the programs 
and a usage map of the Apple II memory aren't dis- 
tributed with the system, Syntauri is reasonably helpful 
in assisting the knowledgeable user with customization. 
(The assembly-language source code is offered for a 
nominal fee.) 



Wave III 

This is a slow, flexible Applesoft program which 
graphically displays the process of building waveforms 
via additive synthesis. The procedure is simple: you are 
queried for "Which waveform?" and then "Which har- 



118 December 1981 © BYTE Publications Inc 



Circle 200 on inquiry card. 



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Software costs are low, too, 
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How to break the 8- 

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The 8088 runs at full speed 
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But don't think you have to stop 
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Relative Performance 


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bit performance barrier 
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Circle 197 on inquiry card. 



r 



Name. 



Title. 



Company.. 
Address__ 



Europe: Intel International, Brussels. Belgium. 
Japan: Intel Japan. Tokyo. United States and Canadian 
distributors: Alliance, Almac/Stroum, Arrow Electronics, 
Avnel Electronics. Component Specialties, Hamilton/Avnet. 
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B12 




Photo 5: Bill Mauchly's eight-track Linden Studio in Ambler, Pennsylvania. In the foreground is the Fairlight Computer Music 
Instrument, the alphaSyntauri keyboard on top of the CMI, the monitor, an Apple II with Mountain Computer music synthesizer 
boards, the Fairlight ASCII keyboard, The Sound Workshop 12-channel mixing console, an Otari eight-track recorder, and various 
outboard equipment in the rack at lower right. The studio is a 100-year-old barn, and the research lab is located a short distance 
away. (Photo by Irene Mohler) 



monic?" until you decide you're done. On each iteration, 
the resultant wave is played back at a constant pitch for 
evaluation. The waveforms available for addition and 
subtraction are band-limited versions of the common 
analog wavetypes: sine, triangle, square, sawtooth, or 
any user-specified complex waveform. This program is 
the most common and useful way of generating 
wavetables. If Syntauri would rewrite Wave III in 
assembly language, it would be capable of instant display 
and, therefore, be a more intuitive feedback loop be- 
tween the creation of waveforms and envelopes. 

Analyzer III 

Fourier analysis of a waveform is the reciprocal to ad- 
ditive synthesis of sine waves. The program takes as its 
input any wave and supplies the harmonic content up to 
any specified harmonic. 

The most creative use for this program that we've 
heard is by Cretones keyboardist Steve Leonard, who 
needed to simulate a Vox portable organ. He used an 
oscilloscope to get a picture of the waveform he wanted, 



then wrote a BASIC program to draw a line segment ap- 
proximation of the wave and write it to a binary file. 
Next, he analyzed the wave with Analyzer III. Using the 
resultant harmonic specification, he resynthesized the 
wave with Wave III. 

Why didn't he just use the line-segment version of the 
waveform7 Steve knew, as the analysis confirmed, that 
some very high harmonics were present in his line- 
segment waveform. When a digital oscillator — like that 
used in Mountain Computer hardware — tries to create 
frequencies above half its sampling rate (above 
16,000 Hz, in this case), the frequencies fold over and 
show up as lower, incorrect frequencies within the audio 
spectrum. This phenomenon is known as "aliasing." (A 
good explanation of aliasing is given in the Computer 
Music journal, volume 2, #2 in "Introduction to the 
Mathematics of Signal Processing," by F R Moore.) These 
stray aliases usually have little to do with the intended 
sound and are objectionable. To reduce their presence, 
care must be taken to limit the strengths of high har- 
monics in a wavetable. 



122 December 1981 © BYTE Publications lnc 



Low cost software 

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EVERY TYPIST AN EXPERT 
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The other consideration is the fundamental frequency 
at which the note will be played. A waveform for a bass 
instrument can get away with richer, higher harmonics. 
Practically speaking, aliasing can be a useful effect in the 
simulation of noise and complex nonharmonic tones. 

Keyboard Architecture 

The alphaSyntauri synthesizer keyboard is a standard, 
two-bus, 61-note, Pratt-Reed organ keyboard. This 
keyboard assembly is found in many commercial musical 
instruments, such as Moog, Arp, and Crumar syn- 
thesizers. Syntauri has added CMOS circuitry, which 
allows the Apple to scan each key's two vertically posi- 
tioned contacts (lower and upper) approximately once 
every 10 milliseconds for make or break conditions. 

After the entire keyboard is scanned, this information 
is compared with a memory map of the last scan and is 
updated if different. A timer, maintained in the com- 
puter's memory, counts the number of scans between 
changes, including the time between closing of the lower 
and upper contacts of each key. This number (in the 
counter when the key is fully down) is used as an index in 
a velocity table, which is in turn applied to the attack rate 
and the final attack volume. The table contains 32 entries 
and allows the production of up to 32 different perceived 
velocities. By altering a value specified in the velocity 
setup program, the inverse relationship of key velocity to 
loudness can be made more or less linear on a scale of to 
7.99. In effect, this varies the keyboard response to 



velocity from linear to logarithmic. 

The keyboard's tuning is organized by a scale table, 
which is set up by the Scale program. Just, well- 
tempered, international, or any scale from 1 to 32 inter- 
vals/octave may be chosen. The standard scale is well- 
tempered and is 12 intervals/octave. (A very concise 
discussion of the alphaSyntauri keyboard can be found in 
a paper presented by Charlie Kellner, Ellen Lapham, and 
Laurie Spiegel at the 67th convention of the Audio 
Engineering Society, New York City, November 1, 1980. 
Reprints are available from Syntauri Corp.) 

One other setup program is Log III, which creates a log 
table for producing attack, decay, and release envelopes. 
Two envelope log table types are available: linear and ex- 
ponential. Linear is best for nonpercussive sounds with 
slower attacks, such as strings and brass. Exponential 
works well for percussive sounds, like pianos and bells. 

The FX Controls 

What would a synthesizer be without some kind of per- 
formance effects? Syntauri and Laurie Spiegel devised 
some neat ways to modify the sound while playing; these 
are dubbed FX. Hitting the space bar and the letter "F", 
you are asked which effect file is desired. The files are text 
type and are prefixed with MOD.nnnnnn. (You don't 
have to type Mod.) Hit Return and you have the newly 
selected effect. The available FX are Timbre Scan, Pitch 
Sweep, and Pitch Bend. 

The effects like vibrato use the game paddles for con- 



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124 December 1981 © BYTE Publications Inc 



Circle 237 on inquiry card. 



SuperSoft's 

Gallery off CP/M Waterworks 




£525 

£ DIAG 
2 Test: 



A system diagnostic package 




DIAGNOSTICS 
Testa: 

• Memory • CPU (8080/8085/Z80) • Terminal • Disk • Printer 
To our knowledge the CPU test is the first of its kind anywhere. Diagnostics 
I can help you find problems before they become serious. A good set of 
diagnostic routines are a must in any program library. Minimal re- 
quirements: 32K CP/M Supplied with complete user manual; $75.00 Manual 
alone; $15.00 

DIAGNOSTICS II: The most comprehensive set of CP/M compatible 
system check-out programs ever assembled. Includes all of 
Diagnostics I. plus: 

• Every test is "submit'-able 

• A complete Spinwriter/Diablo/Qume test has been added 
(Serial Interface only) 

■ Output may be logged to disk 

• Expanded memory test 

• Expanded terminal test 
Expanded disk test 

Diagnostics II provides the next level in system maintenance. 

Requires: 32K CP/M 

Price: $100.00 Manual only: $15.00 



SYSTEM MAINTENANCE 




SUPER-M-LIST: A complete, easy to use mailing list program 
package. Allows for two names, two addresses, city, state, zip and 
a three digit code field for added flexibility. Super-M-List can sort 
on any field and produce mailing labels direct to printer or disk file 
lor later printing or use by other programs Super-M-List is the 
perfect companion to TFS. Handles 1981 Zip Codes! 
Requires: 48K CP/M 
Supplied with complete user manual: $7500 manual alone: $10.00 

TFSText Formatting System: An extremely powerful formatter 
More than 50 commands. Supports all major features including: 

• left & right margin justification • user defined macros 

• dynamic insertion from disk file • underlining and backspace 
TFS lets you make multiple copies of any text. For example: Per- 
sonalized form letters complete with name, address & other inser- 
tions trom a disk file. Text is not limited to the size of RAM making 
TFS perfect for reports or any big job. Text is entered using CP/M 
slandard editor or most any CP/M compatible editor, 
Requires; 24K CP/M 

Supplied with extensive user manual: $85.00 manual alone: $20.00 
Source to TFS in 8080 assembler (can be assembled using stan- 
dard CP/M assembler) plus user manual: $250.00. 



TEXT PROCESSING 



UTILITIES I: A collection of programs that you will find useful and 

maybe even necessary in your daily work (we did!). 

Includes: 

GREP: Searches files for a specified string 

SORT: In core sort of variable length records 

CMP: Compare two fiies for equality 

PRINT: Formatted listings to printer 

PG: Lists files to CRT a page at a time 

. . . plus more . . 
Requires: 24K CP/M 
Supplied with manual on discette: $60.00 

UTILITIES II: Many new programs not available elsewhere. Includes these 
"file" utilities: 

DIFF. Source comparitor 

PR Powerful multicolumn output formatter 

DC Desk calculator 

RPL: Substitute strings in files 

. . . plus more 
Requires: 24K CP/M $60.00 
Supplied with manual on discette 



UTILITIES 




4 



m 



ANALIZA; An amazingly accurate 
simulation of a session with a 
psychiatrist. Better than the famous 
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Requires 48K CP/M. CBASIC2 
Cost $35.00 



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Z8000.CROSSASSEMBLER:Supports: 

full Z8000 syntax, segmented and 

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Requires 56K CP/M $500 00 

1 year mamlenance $300 00 

manual alone $ 50.00 



l^g w 



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On line "Help" system provided with every program package. 



SuperSoft 

First in Software Technology 



CPIM REGISTERED TRADEMARK DIGITAL RESEARCH 



\ * ititiitntiitiitiitiitiitiif^ * A * E BBS 



SSS FORTRAN: The SSS FORTRAN compiler is fast, efficient, and complete 
(lull 1966 ANSI slandard with extensions) The RATFOR compiler compiles into 
FORTRAN allowing the user to write structured code while retaining ihe 
benelits of FORTRAN. The FORTRAN supports many advanced features not 
found in less complete implementalions. including, complex arithmetic, 
character variables, and functions. Complete sequencial and random disk I/O 
are supported SSS FORTRAN will compile up lo 600 lines per minute! Recur- 
sive subroutines with static variables are supported ROMabie " COM" files 
may be generated SSS RATFOR allows Ihe use of coniemporary loop control 
and structured programming techniques SSS RATFOR is similar lo FORTRAN 
77 in that il supports such things as 

• REPEAT ...UNTIL • WHILE • IF...THEN...ELSE 
SSS RATFOR is supplied with source code in FORTRAN and RATFOR. 
System Requirements & Prices: 
SSS FORTRAN requires a 32K CP/M system. 
SSS FORTRAN with RATFOR: $325.00 
SS FORTRAN alone: $250.00 
RATFOR alone: $100.00 
(RATFOR sold only with valid SSS FORTRAN license) 

STACKWORK'S FORTH: A full, extended Forth interpreter/compiler produces 
COMPACT, ROMABLE code. As fast as compiled FORTRAN, as easy to use as in- 
teractive BASIC. 
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itself. 
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Z80 or 8080 ASSEMBLER included. 
Single license. OEM licensing available. 
Please specify CPU type: Z80 or 8080 
Supplied with extensive user manual and tutorial: $175.00 
Documentation alone: $25.00 

TINY' PASCAL II: We still call it Tiny' but it's bigger and better than ever! This is 
the famous Chung-Yuen Tiny' Pascal with more features added. Features include: 

• recursive procedures/functions • integer arithmetic • CASE 

• FOR (loop) • sequential disk I/O * 1 dimensional arrays 

• IF.. THEN. ..ELSE • WHILE • PEAK & POKE 

• READ & WRITE • REPEAT.. .UNTIL • more 
Tiny' Pascal is fast. Programs execute up to ten limes faster than similar BASIC 
programs. SOURCE TOO! We still distribute source, in Tiny" Pascal, on each 
discette sold. You can even recompile the compiler, add features or just gain in- 
sight into compiler construction. 

j Requires: 36K CP/M. Supplied with complete user manual and source on discette: 
$85.00. Manual alone: $10.00 



TERM: A complete intercommunications package for linking your com- 
puter to other computers. Link either to other CP/M computers or to large 
timesharing systems. TERM is comparable to other systems but costs 
less, delivers more and source is provided on discette! With TERM you 
can send and receive ASCII and Hex files (COM too. with included conver- 
tion program) with any other real time communication between users on 
separate systems as well as acting as timesharing terminal. 

• Engage/disengage printer • error checking and auto retry 

• terminal mode for timesharing between systems 

• conversational mode • send files • receive files 
Requires: 32K CP/M 

Supplied with user manual and 8080 source code: $150.00 
Manual alone: $15.00 



ENCODE/DECODE: A complete software security system for CP/M 
Encode/Decode is a sophisticated coding program package which trans- 
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^ SOFTWARE SECURITY f * ■ ^ 

CP/M Formats: 8" soft sectored, 5" Northstar, 5" Micropo- 
lis Mod II, Vector MZ, Superbrain DD/QD 
All Orders and General Information: 
SUPERSOFT ASSOCIATES 
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CHAMPAIGN, IL 61820 
(217) 359-2112 

Technical Hot Line: (217) 359-2691 
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105 JAPAN 



SuperSoft's Masterpiece 
of the Mouth 




troL Timbre Scan actually scans through all the wave- 
forms in the preset master, in a sequence whose rate and 
pitch are controlled by the paddles. Pitch Sweep modu- 
lates the frequency upward into aliasing at a depth con- 
trolled by one of the paddles. Pitch Bend allows for 
dynamic frequency changes through the movement of a 
paddle with one hand, while the other plays the key- 
board. All effects can also be used with vibrato. 

Graphics 

One of the most captivating features of the alphaSyn- 
tauri system is the "Close-Encounters" graphics that ac- 
company the music. A corresponding bar on the screen 
lights up for each key that is down. A captivating and 
entertaining effect results, especially when the sequencer 
is playing back some piece. At a trade show, a spectator 
was overhead saying to her friend, "I've never seen music 
beforel" While this is not a feature we would spend hun- 



dreds of dollars to obtain, it is a great extra as a by- 
product of performance. When the question "What good 
does that do?" arises, we mumble something about the 
ability to visually inspect playing technique. (By watch- 
ing the blocks, it is quite easy to gauge the amount of roll- 
over between adjacent keys. Speaking candidly, though, 
the graphics are just attractive.) 

The Manual 

The alphaSyntauri manual is very much in the spirit of 
the Applesoft tutorial manual — friendly and jovial, 
though a little confusing. It works quite well as a tutorial; 
you can sit down with the instrument, read through the 
manual, and apply things that you learn. The explana- 
tions of synthesis theory are well illustrated. We found 
the "Quick Reference Guide" more useful when we had a 
general knowledge of the system. Neither document has 
an index. 




IF YOU ENJOY MUSIC, WHY JUST LISTEN? 

You and your Apple could be making 
beautiful music together! 
join the thousands of Apple owners who are 
making music — without the years of practice 
needed for conventional instruments. You can 
quickly and easily enter a song from sheet music. 
Just follow the detailed examples and instructions 
provided 

THE PRODUCT. ALF's economical 9-voice Music 
Card MC1 is just $195, the gourmet 3-voice Music 
Card MC16 is $245 (use 2 for 6 voices or 3 for 9). 
Both come with detailed manual, complete soft- 
ware, and cable for connection to your stereo 
system. 

THE SOFTWARE. We're convinced our product is 
by far the easiest to use and most versatile system 
for the Apple. You get many features not available 
in other systems, plus a very large note capacity. 
And no customer has ever reported a "bug'' 
or error. 

THE HARDWARE. ALF strives for the best quality 
possible. No MC1 card has ever been returned 
with a manufacturing defect. 
THE COMPANY. ALF has been making computer- 
controlled synthesizers since 1975. We made the 
first music peripheral for the Apple — and it's still 
one of the most popular. 

Available through Apple dealers, or write for 
more information. 




WANT TO DUPLICATE DISKS QUICKLY? 

ALF's disk duplication service has been a major 
source of quality reproduction for Apple- 
compatible software houses since 1980. Now you 
can use the same techniques for fast and accurate 
reproduction yourself, with ALF's Copy System. 
Why spend over $10,000 for a duplication system 
when for just $595 you can connect the ALF Copy 
System to your own Apple! Copying time is about 
37 to 17.3 seconds, depending on number of drives 
used. That's over 1,600 disks in 8 hours from a 
single system. Are you completely confident of 
your present copying methods? At ALF, accurate 
reproduction is more important than speed. The 
ALF Copy System is designed to produce perfect 
copies every time. 

Special hardware and software copies any stan- 
dard 13 or 16 sector Apple format disk. Hardware 
plugs easily into computer — no permanent 
changes required If you wish to do your own drive 
maintenance, the manual tells how to use stan- 
dard Shugart procedures and accessories, and all 
necessary software is included 

Too busy to get into disk copying? You can still 
count on ALF's convenient copying service. Ask 
about our copy-resistant and "double boot" 
services too! 

Write lor complete details. 




NEED CONVENIENT 
FLOPPY DISK PROTECTION? 

ALF's Floppy Boxes are specially designed to offer 
great protection with more convenient use than 
other methods. They're designed with two layers 
of corrugated cardboard with a special "cross- 
grain" construction for extra strength. The stan- 
dard square size holds 1-3 minifloppies for mailing 
or packing in products The larger rectangular size 
holds minifloppies plus a standard 5V; x 8Vj 
booklet (8Vj x 11 folded in half). Available with an 
adhesive closure tab for use as a mailer (just seal 
with tab, address other side, and mail) Software 
houses: write for details on attractive, protective 
packaging for your products. 

Small quantity price is 75<t for standard box. 

Available singly at computer dealers, in large 
quantities from ALF (New dealer inquiries 
invited.) Aug 81 



A L F PRODUCTS INC. 1448ESTES DENVER, CO 80215 



126 



December 1981 © BYTE Publications Inc 



Circle 11 on inquiry card. 



Circle 68 on inquiry card. 



TflG 








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Applications 

We tried to put the alphaSyntauri through its paces 
and discover what other people were doing with it. Steve 
Leonard, mentioned earlier, uses his onstage with a rock 
band and has developed a set of presets to replace a lot of 
heavier, traditional professional keyboards. We put his 
instruments into action when the rock group Sister Sledge 
was working at Linden Studio. No analog synthesizers 
were available, so keyboard player Steve Gould received 
a mini-lesson in using the alphaSyntauri synthesizer. 
Within five minutes, he was playing independently. The 
Close Encounters theme was heard many times that 
night. 

On the academic side, Stanford University has a com- 
puter-assisted instruction project in the works. The 
curriculum, developed on its PDP-10 by Dr. Wolfgang 
Kuhn, is being adapted to the alphaSyntauri system to 
teach basic music theory. This should be very interesting, 
and I am sure many other universities will implement it. 

Laurie Spiegel, a composer who uses the alphaSyntauri 
system in her work, has too extensive a background in 
computer music composition and programming to cite 
here. But we feel that one of her contributions to the 
alphaSyntauri system is worth mentioning. Laurie has 
one of the earliest Syntauri keyboard prototypes. Even 
before there was really a developed product, she was 
writing her own 6502 programs on her Apple (which is 
also a prototype), to process and interact with the 



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keyboard in interesting ways. 

In a concert series, "Computer in Perfor- 
mance" — presented in New York City during 
1980 — Laurie used a keyboard program she wrote in 
Pascal. An effective PEEK and POKE permutation 
algorithm, it used the keyboard to specify transposition. 
Melodic and harmonic materials were specified by soft- 
ware. There were several processes running which 
specified sets of pitches to be played. Laurie selected 
which sets the program would be permuting, while the 
alphaSyntauri synthesizer specified the base pitch. The 
paddles were used to modify the timbre and effects, and 
the result was musical and interesting. 

A more recent program is a composition which she 
patched into the alphaSyntauri system software. Going 
to the recorder menu and typing "C" (for compose), she 
can build lines of music based on written algorithms 
which are then patched into the main alphaSyntauri 
BASIC program. For example, a small FOR-NEXT loop is 
used to build an arpeggio. Her program asks for the 
number and spacing of the events in the sequence, along 
with a number of simultaneous notes. It will fill a notes 
table with a sequence based on the information supplied 
and the little algorithm which was preprogrammed. This 
is simply one user's own experiment, not an official 
release by Syntauri. (This little composing program is 
just the tip of the iceberg for algorithmic composition.) 

Complaints 

Game paddles are a drag. They are imprecise, don't 
stay where you put them, and waste processor time. I 
really wish the system had a couple of slide potentio- 
meters and a cheap analog-to-digital converter. 

The manual has no index 1 (Syntauri says it's preparing 
one.) The system takes too long to boot up. (Syntauri's 
working on that, too.) Depending on your audio quality 
requirements, the Mountain Computer synthesizer hard- 
ware can be a bit noisy (8-bit digital-to-analog con- 
verters). But it is the best choice when you compare price 
to performance. 

Conclusions 

• The software allows for system expansion. Innovative 
musical ideas or new methods of analysis can be easily in- 
corporated into the operating system. 

• The alphaSyntauri system uses a modular approach for 
the hardware, allowing for future improvements and 
upgrading of the system. This means the system can 
grow, not be outgrown. 

• The software — while some may argue the advantages 
of straight assembly language — is fast when it needs to be 
and slow and accessible where necessary. 

• The real-time interaction with the composer is an im- 
portant improvement. This changes the synthesizer into a 
true musical instrument. 

• The price is obviously more than the average Apple II 
owner can afford. For the serious musician, however, the 
alphaSyntauri's combination of quality sound, good per- 
formance, and price make it well worth the money. ■ 



128 December 1981 © BYTE Publications Inc 



Circle 416 on inquiry card. 



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When we shipped 
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CompuPro" 

BOX 2355, OAKLAND AIRPORT, CA 94614 



division of 




Circle 77 on inquiry card. 



COMPUPRO: 12 WAYS TO A COMPETITIVE EDGE, 

We give you more of what you buy a computer for: to gain a competitive edge in your 
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1. DISK 1 DMA DISK CONTROLLER. Properly imple- 
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RAM 20. With extended addressing or bank select. RAM 
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RAM 21. Configure as 128K x 8 or 64K by 16. $1695 
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8. M-DRIVE. As close as you can come to the solid-state 
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Circle 78 on inquiry card. 



Book Reviews 



AIM 65 
Laboratory 
Manual and 
Study Guide 

Leo J Scanlon 

John Wiley and Sons Inc 

Somerset NJ, 1981 

1 79 pages, softcover 

S7.95 



Reviewed by 
Bob Katz 
248 E 90 St #3B 
New York NY 10028 

The AIM 65 Laboratory 
Manual and Study Guide is 
designed to provide an inex- 
pensive but effective means 
for high schools, vocational 
schools, and colleges to im- 
plement a microprocessor 
computer lab. It is a good in- 
troduction to machine- 
language software tech- 
niques. 

The manual is designed 
only for use with the 
Rockwell AIM 65 computer; 
the monitor commands will 
not work with other com- 
puters. However, students 
who master this manual 
should be able to program 
fluently in 6502 machine 
language and in a dialect of a 
popular 6502 assembly 
language. 

A vocational school that 
trains computer service 
technicians would be 
especially interested in the 
AIM 65 course. People who 
repair hardware must also 
understand software on the 
machine-language level. For 
example, they should be able 
to read and write bytes to 
and from a suspect output 
port and make checks with a 
logic analyzer to see if the 
hardware is at fault. 

In my experience, half of 
all hardware problems are 
due to bad connections. After 
eliminating these, only 20 
percent or so are related to 



bad components. I believe, 
however, that more than 90 
percent of all service prob- 
lems are actually software 
problems. Remember GIGO 
(garbage in, garbage out)7 
Practice work with the AIM 
65 should educate students in 
the complexities— and the 
pitfalls — of software writing. 
They will certainly have 
more sympathy for future 
clients who call for repairs, 
only to discover that the 
problem lies in the software. 
Most computer-repair 
schools have a digital logic 
course or lab in transistor- 
transistor logic and com- 
plementary metal-oxide 
semiconductor devices, a 
Boolean algebra course, and 
a basic electronics course. 
Ultimately, a microprocessor 
computer lab would com- 
plete the program. 

The AIM 65 is a single- 
board computer built by 
Rockwell International and is 
a refinement and extension of 
the popular KIM computer, 
which was developed by 
MOS Technology (now 
Commodore). But the AIM 
has some "big-gun" features 
that successfully emulate 
those of larger systems to 
give computer students a 
taste of the "real world." 

The AIM 65 includes an 
on-board, 20-column thermal 
printer, a companion 
20-character light-emitting- 
diode display, a full-size 
typewriter keyboard, a very- 
interactive monitor and text 
editor, 20 input/output 
ports, and up to 4 K bytes of 
RAM on board. BASIC and 
the two-pass assembler are 
also ROM options. A 
number of cottage industries 
have sprouted to provide pe- 
ripheral support for the ubiq- 
uitous single-board com- 
puter; therefore, a school 
could easily expand one or 
more laboratory stations to 
include an RS-232 interface, 
64 K bytes (or more) of 



memory, DOS (disk operat- 
ing system), and more. 

Leo J Scanlon is documen- 
tation manager for Rockwell 
International. Scanlon's 
writing style is always clear, 
yet pleasantly conversational 
in tone. In 6502 Software 
Design, Scanlon wrote in an 
analytical manner for the 
serious reader who can 
handle large amounts of 
abstract material. I did 
manage to learn the 6502 
language and concepts from 
Software Design before pur- 
chasing or even using my first 
computer. Most people, 
however, are uncomfortable 
with learning in such an 
abstract manner. 

AIM 65 takes another 
approach. It was written for 
those who need the feedback 
that comes from the tactile 
process of experimenting 
with a computer while also 
learning about it. It is an 
effective, modularized, step- 
by-step educational approach 
to using and programming a 
6502-based microcomputer. 
Students are encouraged to 
write their own programs and 
learn debugging techniques. 
Each experiment is well- 
organized, beginning with 
"object" and "pre-lab 
preparation" (reading) and 
ending with "discussion" and 
"procedure." 

Chapter headings include: 
Getting to Know the AIM 65; 
Addition Operations; Sub- 
traction and Logical Opera- 
tions; Program Sequencing; 
Debugging Programs; 
Multiplication Operations, 
with Shift and Rotate; Divi- 
sion Operations; Subroutines 
and the Stack; Unordered 
Lists; Sorting Unordered 
Data; Code Conversion from 
Input; Code Conversion for 
Output; Input/Output; A 
More Powerful I/O Device, 
the R6522 VIA; Interrupts; A 
Timing Program with 
Decimal Output; The Aim 65 
Assembler. 



I've performed several of 
the experiments described by 
Scanlon and can verify that 
this lab manual works quite 
well as a self-study method. I 
recommend it to any pur- 
chaser of the AIM 65 com- 
puter, and I feel it is the best 
learning tool available for the 
novice machine-language 
programmer. ■ 



BYTEs Bits 



Conference 
Proceedings 

In January 1981, the Col- 
lege of Education at Arizona 
State University hosted a 
microcomputer conference 
that was designed to intro- 
duce educators and adminis- 
trators to the applications of 
microcomputers in the class- 
room. The conference pro- 
ceedings are now available in 
a 340-page book that includes 
more than 30 articles. Among 
the titles are "Instructional 
Techniques for Teaching 
BASIC Programming to Ele- 
mentary Children," "Using 
Computers with the Blind 
and Deaf Children," "Manag- 
ing Instruction with a 
Micro," 'The Challenge of 
the 1980's: Computer Liter- 
acy," and "Microcomputers 
in High School Physics." 

The proceedings are avail- 
able for $10 from Dr Gary 
Bitter, Arizona State Univer- 
sity, Payne B203, Tempe AZ 
85287. ■ 



132 December 1981 © BYTE Publications Inc 



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Circle 209 on inquiry card. 



Color Computer from A to D 

Make Your Color Computer "See" 
and "Feel" Better 



The Radio Shack Color Computer 
has an amazing amount of circuitry 
built into it for the price. One of its 
most interesting features is the joy- 
stick interface, which allows you to 
control the screen cursor position by 
the use of two joysticks. Actually, 
this use of the joystick is one of the 
most mundane applications of the 
built-in analog-to-digital (A/D) cir- 
cuitry. How would you like to use the 
joystick inputs for reading in tem- 
perature, intensity of light in a room, 
or other real-world physical quan- 
tities? And do it with only a few addi- 
tional inexpensive components? How 



First in a series 



William Barden Jr 

28122 Orsola 

Mission Viejo CA 92692 



would you like to have four channels 
of data coming into the Color Com- 
puter, making it a data-acquisition 
system for storing and processing 
real-world data? 

In this article I'll show you how to 
accomplish all of these things. The 
Color Computer hardware that han- 
dles the joystick inputs, the software 
that drives the input electronics, and 



This is the first article of a series 
devoted to Radio Shack computers: 
TRS-80 Model I, Model III, and the 
newest member of the Tandy family, 
the Color Computer. The emphasis 
will be on using the Radio Shack sys- 
tems to interface to the real world. In 
some cases, special-purpose hardware 
that connects to the computer input/ 
output ports will be used; in other 
cases, no special hardware will be re- 
quired, because the computer systems 
provide everything necessary. 

In general, a systems approach to 
the problem of interfacing will be used. 
Too often the advocates of hardware 
and software are separated by a wide 
gulf. We've all seen implementations in 
a computer system where an applica- 



tions problem is solved by interfacing a 
custom-designed device that uses 315 
integrated circuits; in this case, one 
suspects the designer has a strong hard- 
ware background. Conversely, there's 
the implementation where everything 
is "software-driven" in a 2000-instruc- 
tion, hand-coded, machine-language 
program using a single computer in- 
put/output line; the designer here is 
obviously from the software clan. I'll 
attempt to take a middle road. After 
all, the important point is that a com- 
puter system can be used to accomplish 
some pretty spectacular real-world 
things; I'll show how to do this in the 
most efficient fashion possible, using a 
balance of hardware and software 
techniques. 



the implementation of real-world in- 
puts will all be investigated. [For 
background information on the Color 
Computer's circuitry, see Tim Ahrens 
et ah, "What's Inside Radio Shack's 
Color Computer?" March 1981 
BYTE, p. 90.] 

Joystick Circuitry 

First, a look at the hardware. 
Figure 1 shows a block diagram of the 
Color Computer joystick circuitry. 
Two joysticks, each having an X and 
a Y channel, connect to a data selec- 
tor that selects one of the four chan- 
nels. The output of the selected chan- 
nel goes to a comparator. 

The second input to the compara- 
tor is a software-controlled reference 
voltage. This voltage comes from a 
digital-to-analog converter (DAC) 
driven by six programmable data 
lines. (Yes, that's "digital-to-analog," 
even though the subject of this article 
is analog-to-digital. I'll explain why 
the DAC is needed later on.) The data 
lines come from a peripheral interface 
adapter (PIA). 

The output from the comparator 
goes to one input line of a second 
PIA. A more detailed diagram of the 
electronics is shown in figure 2. Parts 
placement on this diagram corre- 
sponds to the functional blocks of 
figure 1. I'll refer to figure 2 in the fol- 



134 December 1981 © BYTE Publications Inc 



TYPE'N TALK" 

A«? "o SPEECH SYNTHESUE. 




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• Unlimited vocabulary 

• Built-in text-to-speech 
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• 70 to 100 bits-per-second 
speech synthesizer 

Type-'N-Talk;" an important technological 
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with an unlimited vocabulary. You can 
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You operate Type-'N-Talk'" by simply typ- 
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Your typewritten words are automatically 
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system's microprocessor-based text-to- 
speech algorithm. 

The endless uses of 
speech synthesis. 

rype-'N-Talk' u adds a whole new world of 
speaking roles to your computer. You can 
program verbal reminders to prompt you 
hrough a complex routine and make your 
computer announce events. In teaching, 
the computer with Type-'N-Talk'"can 
actually tell students when they're right 
or wrong — even praise a correct answer. 
And of course, Type-'N-Talk"is great fun 
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Text-to-speech is easy. 

English text is automatically translated 
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with Type-'N- Talk!" ASCII code from 
/our computer's keyboard is fed to 
Type-'N-Talk'through an RS 232C inter- 
lace to generate synthesized speech, 
fust enter English text and hear the verbal 



response (electronic speech) through your 
audio loud speaker. For example: simply 
type the ASCII characters representing 
"h-e-1-l-o" to generate the spoken 
word "hello." 

TYPE-'N-TALK "has its 

own memory. 

Type-'N-Talk^has its own built-in micro- 
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Data switching capability 
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Place Type-'N-Talk " between a computer 
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Selectable features make 
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Type-'N-Talk "can be interfaced in several 
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Connect it directly to a computer's serial 
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Using unit assignment codes, multiple 
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Unit addressing codes allow independent 
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your printer. 



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• Baud rate (75-9600) 

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The Votrax Type-'N-Talk" is one of the 
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the market. It uses the least amount of 
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E2E 



LEFT JOYSTICK 




RIGHT JOYSTICK 




DATA 
SELECTOR 



COMPARATOR 



COMPARATOR 
OUTPUT 



PIA 



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LINES 



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Figure 1: Color Computer joystick circuitry, block diagram. 



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lowing discussion and explain some 
of the parts for you software types. 

Joysticks. The joysticks are simply 
variable resistors, or potentiometers, 
as shown in figure 3. Move the joy- 
stick control in the up-down direction 
only, and the Y potentiometer wiper 
moves across the potentiometer, 
varying the resistance from to 
100,000 ohms (Q). Move the joystick 
control in the right-left direction 
only, and the X potentiometer wiper 
varies the resistance from to 
100,000 Q. Every position of the joy- 
stick can be translated into X and Y 
coordinates, with resulting X and Y 
positions and corresponding resis- 
tance values. 

Because both potentiometers are 
connected between +5 volts (V) — 
from the Color Computer — and 
ground, the voltage output to the X 
and Y channels varies between ap- 
proximately V (up or left position) 
and +5 V (down or right position). 
A switch on each joystick connects 
another input pin (pin 4) to ground 
when it is pressed. 

Data Selector. The MC14529 is an 
analog switch. This device selects 
one of four input channels and routes 
it to the output W. The signal is not 
otherwise processed as it passes to the 
LM339 comparator, so the voltage in- 
put from one of the channels is fed 
unchanged to the LM339 positive ( + 
or noninverting) input. 

The selection of the channel is 
determined by two select lines, SELl 
and SEL2. These lines are outputs 
from the second 6821 PIA. I'll discuss 
the PIAs in a moment, but for now, 
simply note that you can select one of 
the four channels easily by changing 
SEL1/SEL2 to 00, 01, 10, or 11. 

The Comparator. The LM339 is a 
common device that compares two 
voltage inputs. The inputs are two 
DC levels which can vary from V to 
some positive voltage. The output is 
either on or off. In this case, the two 
inputs will vary from to +5 V (ap- 
proximately), and the output will be 
either V (+ input greater than — 
input) or +5 V (+ input less than — 
input). The output, then, represents a 
binary or 1 and reflects the com- 
parison of a joystick voltage and a se- 
cond input called CASSOUT. 



138 December 1981 © BYTE Publications Inc 



Circle 49 on inquiry card. 



SEL2 



h5V 



•lOOfl 



LEFT 

JOYSTICK 

PLUG 



RIGHT 

JOYSTICK 

PLUG 



!>5 loyi-r 

4 2 )y 

<° 3 Or 



r 



TV TT 
KSJr 



}1- 

0.02 



(77 



ADDRESS 
$FF20 



ADDRESS 
$FF00 



ADDRESS 

$FF03 

$FF01 




Figure 2: Detailed joystick circuitry (parts placement cor- 
responds to that in figure 1). 



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December 1981 © BYTE Publications lnc 139 



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BYTE December 1981 141 



Digital-to-Analog Converter. Now 
for the seemingly out-of -place DAC. 
In short, it provides a mechanism for 
"guessing" the value of the currently 
selected joystick channel. You might 
think of it as a guess-my-number af- 
fair. 

The six buffers of the MC14050B 
and the resistor network make up the 
DAC. The DAC takes the six lines 
labeled PA7 through PA2 and con- 
verts the binary values of 000000 
through 111111 into corresponding 
voltages of to +5 V DC. Because 64 
separate values are represented over 
this range (111111 is 63), the voltages 
represented will be in steps of % t V 
(approximately)— V, % 4 V, 10 / 64 V, 
15 / 64 V, ... up to »% 4 V (5 V). 

The method used for this conver- 
sion is a voltage-divider resistor net- 
work, where each resistor produces a 



BUTTON 
SWITCH 



weighted voltage. The output of each 
MC14050B buffer is either or +5 V 
(approximately). If the buffer output 
is V, the resistor associated with the 
buffer can be considered to be at 
ground; if the output is +5 V, the 
resistor can be considered to be at 
+ 5 V. The resulting resistor network 
for a typical configuration is shown 
in figure 4. The output voltage is the 
total voltage from ground to the out- 
put point. Table 1 shows approxi- 
mate output voltages for the range of 
input values. 

The PI A. The PIA is Motorola's pe- 
ripheral interface adapter, basically a 
20-line device in which most lines can 
be programmed as inputs or outputs. 
In the standard Color Computer con- 
figuration, PIA lines feeding the DAC 
are assigned hexadecimal address 
$FF20; PIA lines selecting the channel 



rr~i 




100K /h 

X POTENTIOMETER 



V CHANNEL 



DIN PLUG 
TO COLOR 
04 2p / COMPUTER 



X CHANNEL 



Figure 3: joystick electronics; the joysticks are relatively simple devices. 



of the data selector are assigned hexa- 
decimal address $FF01; and the PIA 
line for JOYIN is assigned hexadeci- 
mal address $FF00. [Editor's note: 
Following 6809 conventions, all hexa- 
decimal values are prefixed with "$". ] 
Other lines are involved with the 
PIAs — lines to read the keyboard, 
lines to handle RS-232 communica- 
tion, and so forth — but the lines per- 
taining to the joystick inputs are the 
only ones shown in figure 5. 

Each set of lines is memory- 
mapped in the Color Computer; us- 
ing BASIC'S tools, a PEEK at 65280 
can be used to read the JOYIN bit, 
while a POKE to 65312 will output a 
value to the DAC. 

Joystick Software 

From here on, the problem is "sim- 
ply a matter of programming." The 
first task is to find the X/Y position of 
either joystick. The algorithm for do- 
ing this is fairly simple: 

1. Select the joystick and X/Y 
channel by sending data to the 
SEL1/SEL2 lines. To select the right 
joystick and X, for example, a must 
be sent to bit 3 of decimal address 
65283 and a 1 output to bit 3 of deci- 
mal address 65281. 

2. The input from the joystick is 
now at the + input of the com- 
parator. Assuming you aren't playing 
a hot game of Space Invaders, that in- 
put should remain relatively constant 
for some period of time, although in 
normal use it could be fluctuating 
from to +5 V in Vi second or less. 

3. Send a value of binary 100000 



DIGITAL. INPUT- 



+ 5V 



REPRESENTS 
101101= 

*5 10 



1 


PA2 





PA3 


1 


PA 4 


1 


PA 5 





PA 6 


1 


PA 7 



M>^ 



H> 



— > 

+ 5V r 



7^> 



ov 



324K 
-wv 

0V 162 K 
— wv — 

80.6K 
— Via — 



N^ +5 V 40.2K 
^ — — VW, — 

^ 20K 



> 



+ 5V 10K 

— Wr 



•100K 



+ 5V 



-324K S80.6 540.2 S10K J100K 



-HZ> = 



-O = 



;20K ^lOOK 




ANALOG OUTPUT 



Figure 4: This diagram shows how a typical digital input is converted into an analog output. 

142 December 1981 © BYTE Publications Inc 



Circle 314 on inquiry card. 




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V 



144 December 1981 © BYTE Publications Inc 



J 



(decimal 32, or about +2.5 V) to the 
DAC by using a POKE 65312,128. 

4. Look at the output of the com- 
parator by doing a PEEK (65280) and 
testing bit 7 by performing a logical 
AND with 128. If the output is a 0, 
the channel value is less than the out- 
put from the DAC. In this case, take 
half of the remaining range (binary 
010000, decimal 16, or about 1.38 V) 
and try again. If the output is a 1, the 
channel value is greater than the out- 
put from the DAC. In this case, take 
half of the remaining range (binary 
110000, decimal 48, or 3.69 V) and 
try again. 

5. Repeat this process six times. 
Each time, take one-half the remain- 
ing range and try again. At the end of 
the six tries, take the value most re- 
cently output; it will be within s l bi of 
the actual voltage produced by the 
joystick. 

Savvy readers will recognize this 
algorithm as our old friend the binary 
search. In this case, a binary search 
has been used to converge on the X or 
Y input voltage by successive approx- 
imation. To prove that this method 
does work, run the BASIC program 
shown in listing 1. This program 
zeroes in on the X channel of the right 
joystick. Move the joystick and the 
program will report back the new X 
position for each iteration. 

BASIC Joystick Commands. The 
JOYSTK command in Color BASIC 
accomplishes the same function as the 
program in listing 1. The format of 
the command is 



JOYSTK (j) 

where / is for the right joystick X; 1 
for the right joystick Y; 2 for the left 
joystick X; and 3 for the left joystick 
Y. JOYSTK(O) must be executed be- 
fore JOYSTK(l), (2), or (3) can be re- 
turned. 

As with other BASIC operations, 
there is a limit to how fast JOYSTK 
can be performed. Assuming you 
want to read the X/Y coordinates of 
one joystick (see listing 2), the speed 
of operation is about 23 X/Y readings 
per second. This is not too bad but 
doesn't allow such things as smooth 
plotting of points on the screen dur- 
ing rapid joystick movement, as in 
listing 3. 

Machine Language. The answer to 
a faster reading of the joysticks, as 
you might suspect, is in 6809 machine 
language. Two driver subroutines in 
Color BASIC are associated with the 
joysticks: one to select the joystick 
channel and one to read all four chan- 
nels into four page-zero locations. 
The Select-Joystick subroutine in Col- 
or BASIC is at location $A9A2; the 
Read-Joystick is at $A9E0. Listings 4 
and 5 show the disassembled code; 
I've added program commentary in a 
separate text box (see page 160). 

Other Uses for A/D Inputs 

As the foregoing discussion has 
demonstrated, a built-in set of four 
A/D channels resides in the Color 
Computer — channels in which the in- 
put voltage may range from to 



MEMORY 
ADDRESS 

$FF20 
$FF00 

$FF01 
$FF03 



BYTE 

7 6 5 4 3 2 10 



D TO A OUTPUT 


X X 



X X X X X X X 



■COMPARATOR OUTPUT (JOYIN) 



X X X X XXX 



c 



LSB OF DATA SELECTOR 



X X X X XXX 



u 



MSB OF DATA SELECTOR 



Figure 5: The Color Computer's PIAs are memory-mapped. A single memory-mapped 
byte has several functions on the bit level. 

Circle 181 on inquiry card. > 



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+5 V DC and in which data can be 
sampled at rates of up to 2500 sam- 
ples per second for a single channel. 
There are many other uses for these 
channels. 

Electrical Analogs. Many physical 
quantities can be represented by an 
electrical analog of voltage, resis- 
tance, or current. A thermistor, for 
example, changes its resistance in ac- 
cordance with temperature. Certain 
types of crystals generate a voltage 
when stressed; thus, crystal micro- 
phones can produce an output 
voltage in step with sound input. 
Photoresistors change their resistance 
values when subjected to varying 
light intensities. 

One problem with many types of 
transducers like these is that they are 
not linear. Equal changes in the phys- 
ical quantity do not produce equal 
changes in the electrical property 
over a wide range. Manufacturers 
strive to maintain linearity in the de- 
vices, and, as a result, the transducers 
become expensive. Using the Color 
Computer A/D inputs, you can com- 



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because you can easily convert input 
values to the corresponding physical 
values by use of a conversion table. 
As a result, you can use many "gar- 
den variety" devices for transducers. 

Another powerful aspect of the 
Color Computer is that you can do 
more than just read instantaneous in- 
put values. You can use the Color 
Computer as a data-acquisition de- 
vice. Inputs can be sampled many 
times a second and then stored in 
memory, on cassette, or on disk. You 
can retrieve the input data as often as 
required and process them in any way 
you wish. 

Following are illustrations of two 
types of real-world inputs that use the 
A/D inputs of the Color Computer, a 
light detector and a thermometer. 
You may be amazed at how simple 
this can be. 

Standard Plug. As a first step, 
make a standard plug for the A/D in- 
puts. The standard joystick plug is a 
5-pin DIN male plug, which Radio 
Shack sells in most stores. Be certain 



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to get a "thin-walled" type; the 
thicker plastic type will not fit in the 
jack. Use any four-conductor wire, or 
four single Wires, to connect to the 
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for the pushbutton switch, although 
its use is not detailed in this article. 



Listing 1: A BASIC program that ac- 
complishes an A/D conversion on the 
right joystick's X-coordinate. The pro- 
gram reads the hardware directly for the 
sake of illustration; the BASIC language 
offers a single command (JOYSTK) to do 
the same thing, as shown in listing 2. 

90 REM SELECT RIGHT, X 

100 A = PEEK(65283) 

110 A = A AND 247 

120 POKE65283.A 

130 A = PEEK(65281) 

140 A = A AND 247 OR 4 

ISO POKE 65281, A 

160 REM SETUP VALUE, DELTA 

170 V = 128: D = 64 

175 REM BINARY SEARCH HERE 

180 POKE65312,V 

190 A = PEEK(65280) 

200 A = A AND 128 

210 IF A = THEN V = V - D ELSE 

V = V + D 

220 D = D/2 

230 IF Do 1 THEN GOTO 180 

235 REM NOW GET 6 LS BITS 

240 V = V AND 252 

250 V = V/4 

260 PRINT V 

270 GOTO 100 



Listing 2: A typical use of BASIC com- 
mands to read the X- and Y -coordinates of 
the right joystick. Line 130 keeps track of 
how many times the joystick has been 
read; this program obtains 23 X/Y read- 
ings per second. 

100 REM TYPICAL JOYSTK PROGRAM 

110 A = JOYSTK(O) 

120 PRINT JOYSTK(0),JOYSTK(1) 

130 1 = 1+1 

140 GOTO 120 



Listing 3: This BASIC program shows 
that the JOYSTK command is too slow to 
keep up with rapid joystick movements; 
you can't get a smooth plot on the screen 
unless you move the stick very slowly. 

100 REM PROGRAM TO PLOT POINTS 

FROM JOYSTICK 
110 PMODE 4,1: PCLS: SCREEN 1,0 
120 PSETaOYSTK(0)*4JOYSTK(l)*3) 
130 GOTO 120 



146 December 1981 © BYTE Publications Inc 



Circle 345 on inquiry card. 



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Input 


Input 


Value Output 


Value Output 


0.230 


32 2.53 


1 0.302 


33 2.61 


2 0.373 


34 2.68 


3 0.444 


35 2.75 


4 0.517 


36 2.82 


5 0.588 


37 2.89 


6 0.659 


38 2.96 


7 0.731 


39 3.04 


8 0.805 


40 3.11 


9 0.876 


41 3.18 


10 0.947 


42 3.25 


11 1.01 


43 3.32 


12 1.09 


44 3.40 


13 1.16 


45 3.47 


14 1.23 


46 3.54 


15 1.30 


47 3.61 


16 1.38 


48 3.69 


17 1.45 


49 3.76 


18 1.52 


50 3.83 


19 1.59 


51 3.90 


20 1.67 


52 3.98 


21 1.74 


53 4.05 


22 1.81 


54 4.12 


23 1.88 


55 4.19 


24 1.95 


56 4.26 


25 2.03 


57 4.34 


26 2.10 


58 4.41 


27 2.17 


59 4.48 


28 2.24 


60 4.55 


29 2.31 


61 4.62 


30 2.38 


62 4.69 


31 2.46 


63 4.76 


Table 1: The Color Computer's D/A 


circuit converts values from to 63 in- 


to voltages from 0.230 to 4.76 V. The 


resultant voltage can then be compared 


with the voltage level from one of the 


joystick input channels. By a method 


of successive approximation, software 


can "measure" the voltage accurate to 


within % 4 V. 



A Light Detector 

The light-detector application uses 
just two components attached to the 
right joystick X channel as shown in 
figure 7. The primary component is a 
cadmium sulfide (CdS) photocell, 
which currently costs $1.29 in Radio 
Shack stores. Its resistance is depen- 
dent upon the amount of light strik- 
ing it and varies from about 5 
megohms (Mfl) (5 million ohms) in 
complete darkness (where it was 
hard to read the ohmmeter) to about 
20 fi in direct sunlight. Some other 
readings are shown in table 2. 

Obviously, this is quite a wide 
range. For this example, the normal 
house interior settings, out of direct 
sunlight, were chosen for a program 
that would determine when the room 
was adequately lighted — a range of 
about 500 to 5000 Q. The input 
voltage V to the channel is given by: 

V = R1/(R1 + Re,) X 5 

where R„ is the resistance of the 
photocell and Rl is the resistance of 
the second component (a V 4 - or 
V 8 -watt (W) carbon resistor, which 
costs about $.25 or less). For a mid- 
point R„ of 2750 Q, Rl should be 
2750 £2. The closest standard resis- 
tance value of 2200 A was used in the 
example. Vary the resistance as re- 
quired for the light conditions you are 
testing. 

A potentiometer with the center 
and one outer pin tied together (ac- 
tually a rheostat) could be substituted 
for the fixed resistor to allow this cir- 
cuit to be used for a variety of ap- 
plications. (Both the fixed resistor 
and the potentiometer are available 
from Radio Shack and other elec- 
tronics parts stores.) 

You read channel using the 



Condition 






Reading (ohms) 


Facing sun 








20 


Sunlit outdoors 








30 


Overcast outdoors 








50 


Shaded outdoors 








100 


Inside house, facing window 








180 


Inside house, facing interior 








830 


Artificially lighted (bright) room 








2200 


Interior of closet, swathed in old racoon coat 








5 M 


Table 2: Readings taken with the light detector. The unit 


is more 


light 


sensitive than 


the human eye, detecting differences where the human eye 


sees 


none 





148 December 1961 © BYTE Publications Inc 



Circle 63 on inquiry card. 



Price 

Performance 

Reliability 




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BASIC JOYSTK(O) command or by 
calling the joystick assembly-lan- 
guage subroutine. 

This light-detector circuit could be 
used for a number of things: an elec- 
tronic exposure meter for a dark- 
room, a light-level detector for artifi- 
cial lighting, the aiming of solar 
panels (with an output to control 
panel positioning), or burglar alarms 
(a detectable drop in output occurs as 
a person walks past the sensor). In 
my tests, the CdS photocell was sensi- 
tive enough to detect differences in 
clothing color and the whiteness of 
various types of paper. Many of the 
differences were not discernible by 
the human eye. 

A Thermometer 

The thermometer application also 
uses two components (shown in 
figure 8). One is a thermistor. A ther- 
mistor's resistance varies with am- 
bient temperature. A rather gross 
type of thermistor, a replacement 
television thermistor, was used for 
this application. It has a resistance of 
about 120 fi at 25 degrees Celsius (°C) 
and about 1.8 Q at 65°C. A ther- 
mistor of this type has a slow 
response to temperature changes but 
is inexpensive ($2.20). Better-quality 
thermistors, over a wide range of 
resistance values, are available from 
manufacturers' representatives and 
are priced from $6 to $10. Choose one 
with a resistance in the 10-kilohm 
(kfi) range to reduce the effect of the 
100-fi resistor in series with the +5 V 
pin. 

A plot of the values obtained by 
reading JOYSTK(O) is shown in figure 
9. Even with this unsophisticated 
thermistor, a temperature resolution 
of 3 to 4 degrees at lower tempera- 
tures was achieved. (The effect of 
100 Q resistance was less 
pronounced.) This particular ther- 
mistor took several seconds to res- 
pond to changes in temperature, 
though. It's easy to see that many in- 
teresting temperature applications 
could be implemented with this sim- 
ple circuit: measurement of liquid 
temperature, fire detection, flow 
gauges (moving fluid cools the ther- 
mistor), a weather station, and the 
like. 



-RIBBON CABLE OR OTHER (NOT CRITICAL) 

X CHANNEL (PIN1) 
Y CHANNEL (PIN 2) 

GROUND LEAD (PIN 3) 
+ 5 VOLTS (PIN 5) 




TO COLOR 
COMPUTER 
LEFT OR RIGHT 
JOYSTICK JACK 



Figure 6: A five-pin "standard" plug, DIN-type, for connecting external devices to the 
Color Computer's joystick input jack. 




// 



CdS 

PHOTOCELL 

(RADIO SHACK #276-116) 



* 2200 OHM 
RESISTOR 




* ALTERNATIVE RESISTOR 
10K POTENTIOMETER 



Figure 7: The light detector components and connections. 



THERMISTOR 

:GC#25-931-F 

120il COLD(65°C) 



GROUND 




Figure 8: The thermometer detector components and connections. 



150 December 1981 © BYTE Publications Inc 



MORROW PI 

Leading edge technology 
in hard disk systems. 



Complete systems. Morrow 
Designs hard disk subsystems 
are delivered complete with hard 
disk, controller, cabinet, power 
supply, fan, cables and CP/M" 
2.2 operating system. 
Widest range. Morrow Designs 
offers the widest range of hard 
disk systems available from a sin- 
gle supplier. b l K 8," 14." Five to 
over 100 megabytes of formatted 
hard disk storage. $2,995 to 
$17,980. Cost effective systems 
that work. And keep working. 
S-100 and more. Morrow Designs 
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Reliable systems. Morrow Designs is com- 
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your money. 




524-2101. 
available. 



Experience. As of April, 1981, 
there were over fifteen hun- 
dred Morrow Designs hard disk 
systems successfully installed. 
In fact, over 200 independent 
systems integrators now use 
our hard disks to solve their 
mass storage problems. 
Performance answers. Morrow 
Designs hard disk systems have 
been benchmarked against all 
other systems. None is faster 
under CP/M. Morrow Designs 
hard disks operate at 10 times 
the speed of a floppy disk 
drive. Transfer rates range from 
590,000 bytes to 900,000 bytes 
per second. That kind of perfor- 
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Cost effective answers. Compare 
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to anything presently available 
for S-100 systems. You'll find 
Morrow's price/megabyte/ 
performance ratio to be 
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disk systems technology 
earned us leadership in 
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that may have earned us 
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Reader Service Number 
for our full line data sheets. 
Can't wait? Call us at (415) 
And yes, OEM quantity prices are 
LOOK TO MORROW FOR ANSWERS. 



MORROW OE5IGN5 



*CP/M is a trademark of Digital Research. 
"Northslar is a trademark of North Star Computers, Inc. 
***Cromemco is a trademark of Cromemco, Inc. 
""Exidy is a trademark of Exidy Corporation, 

Circle 287 on inquiry card. 



5221 Central Avenue, Richmond, CA 94804 
(415) 524-2101 



n 



The New Idea 
from TeleVideo 




*CP/M® is a registered trademark of Digital Research, Inc. 
MmmOST® is a registered trademark of TeleVideo Systems, Inc. 




stems. 





Circle 411 on Inquiry card. 



All the newest technology 

There are two versions available to you. The 
Model TS802 computer features two S^-inch 
floppy disks for 1 Mbyte of on-line storage, a 
Z80A microprocessor, 64K of RAM memory, 
and a 4K EPROM for diagnostics. The Model 
^_^^^^ ^^ TS802H computer has one 5%-inchWin- 

1 TB^J^M 4 ^ Chester disk drive for 10 Mbytes of on-line 

L*^ I I l PA ^ata storage, backed by a 500 Kbyte mini- 
^*^^*^"^ ^ floppy disk unit. The 802H also features the 

Z80A microprocessor, 64K of RAM memory 
and a 4K EPROM for diagnostics. 

Both versions come in a handsome inte- 
,-n a •» grated workstation enclosure that conve- 

r laeaS to WOrK. nienfly includes both the easy-to-read CRT 

display and data storage modules in a single 
?o has always been desktop unit. The fully detachable keyboard 

* with new ideas, provides an extra dimension of flexibility, 

t comes to small And both computers have three ports: two 

;ss computers and RS232 serial ports for rates up to 19.2 Kilo- 

lerals designed to baud, and one unique TeleVideo RS422 net- 

T more value for work serial port for rates up to 800 Kilobaud, 

loney. With the Future in Mind 

iw, we'd like to take The Model TS802 computer was built to 

opportunity to in- get the job done today. . . and tomorrow. Use 

uce our latest new it as a stand-alone computer, or hook it up 

i computer— the and use it as the foundation for part of an 

del TS802. It's expanding network -when the time comes. In 

ded with new tech- stand-alone mode our TS802 series uses the 
logical benefits, and CP/M* operating system. In multi-user 
eked by the com- mode, each TS802 station runs CP/M* under 

iny that streaked to TeleVideo's unique MmmOST® networking 

3 No. 1 position executive. More application software is 

mong independent available for CP/M* than any other 

uppliers of smart operating system. 

erminals by getting . The Model 802 computer is priced at only 

its new ideas to $3495. And the Model TS802H is only priced 

market first. at $6995. And they offer new idea features 

you might have to pay $30, 00Q elsewhere. If 
you're ready to get down to business, contact 
us today for more information about our 
'New Idea' Model TS802 computers. 

Tfel^ided 

TeleVideo Systems, Inc. 
1170 Morse Ave. Sunnyvale, CA 94086 
(408) 745-7760 
800/538-7633 (toll-free outside CA) 

CALIFORNIA Santa Ana 714/557-6095; Sunnyvale 408/745-7760 GEORGIA Atlanta 404/255-9338 

TEXAS Dallas 214/980-9978 ILLINOIS Bloomingdale 312/351-9350 

MASSACHUSETTS Boston 617/668-6891 NEW YORK /NEW JERSEY 201/267-8805 

UNITED KINGDOM West End Surrey 44-9905-6464 



Putting new ideas to work. 



45 
40 
35 

30 

JOYSTK(O) 
READING Z5 

20 

15 

10 

5 





X 



10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 
TEMPERATURE (°F) 



Figure 9: Readings taken with the thermometer; notice that the device is almost linear in the 80-180°F range. 



Other Applications 

Don't hesitate to try other trans- 
ducers with the joystick inputs. Any- 
thing that can resolve physical quan- 
tities into resistance or voltage can be 
measured by the Color Computer 
joystick inputs: 



• A small DC motor, for example, 
might be used in reverse as a gen- 
erator. Driven by anemometer-type 
wind cups, the motor would generate 
a voltage proportional to wind speed 
which could be applied directly 
across pin 3 (ground) and pin 1 (X in- 
put). (Some amplification by a single 



transistor might be necessary.) 

• A solar cell can be used in a similar 
fashion. Tie its output directly to pins 
1 and 3 to read voltage generated by 
sunlight striking the cell. 

• Used with a microphone and small 
amplifier, the Color Computer could 
also act as a sound detector for 




Solomon 

Scries" 

Software 

The Wise Business Decision 

...EASY to Sell 
Because It's... 

EASY TO SET UP 

The Solomon Series Is a family of applications 
software designed to run on a Z-80 processor with 
64K of memory and CPfM* 2.xx. It comes with 
utility programs which allow Solomon to work on 
different terminals and printers. You can also con- 
trol what programs are located on which diskette 
or drive, allowing Solomon to be set up for 
different floppy and hard disk configurations. All 
Solomon systems utilize a single database 
managed by the MDBS* database manager so 
there Is only one data file. 

EASY TO DEMONSTRATE 

A Demonstration/Tutorial system Is available for 
each Solomon package. This system Includes all 
the screens and reports for that system plus a 
database with examples appropriate for demon- 
stration. The demonstration system Is available 
for a fraction of the cost of a full system keeping 
dealer startup costs down. 

EASY TO CUSTOMIZE 

Authorized Dealer Training Is provided which 
describes the design of Solomon and how to 
modify It. Authorized Dealers are provided with a 
Dealer Technical Manual which explains the struc- 
ture of Solomon and describes records and data 
Items used in the database. Solomon Is written 
In the highly structured, efficient PUI-80* 
programming language. TLB offers its Authorized 
Dealers a Source Code Subscription Service to 
provide the source code needed for customization. 



EASY TO INSTALL 

Because Solomon software Is built around a single 
database managed by MDBS , It Is easy to 
Install. There Is only one system to learn, one 
manual to use, one data file to backup. A Dem- 
onstration Tutorial system carries the operator 
through all the processes Involved In Initializing 
the database and operating the system on a day 
by day basis. 

EASY TO OPERATE 

Solomon software Is easier to use because It 
achieves a new level of Integration for micro com- 
puters. All modules are available through pass- 
word protected menu selections. Screens are 
designed to resemble forms familiar to the opera- 
tor. All input Is verified and updated as it Is 
entered - there are no reiected transaction reports 
because Solomon will not accept invalid Input. All 
reports are up-to-date and available as of the latest 
transaction. Use of the MDBS database manager 
eliminates file handling by the operator. There 
are no sorts to run or flies to post at month-end. 
Every screen and report is cross referenced to an 
easy-to-use Reference Manual. 

EASY TO SUPPORT 

It Is easy to support your customer because TLB 
supports you, with a Dealer Training Program, a 
Dealer Technical Manual, Source Code Subscrip- 
tion, a Tutorial/Demonstration System, Dealer 
Bulletins, and telephone support. Solomon uses 
forms which are readily available through Moore 
Business Forms and NEBS. A query package Is 
available from MDBS which allows ad hoc reports 
to be generated from the Solomon database. 

EASY TO BUY 

TLB understands the effort required to sell, Install 
and support an applications software system. 
Dealer discounts for Solomon Software and 
support materials reflect TLB's appreciation of 
that effort. 



To learn more about this remarkable new family 
of accounting software, call or write today. 

SOLOMON I 

GL, AP, AR, Invoicing, Fixed Assets, Payroll, 
Address Maintenance 

SOLOMON II 

GL, AP, AR, Invoicing, Fixed Assets, Payroll, 
Address Maintenance, Job Costing 



1 

I — I Yes, please send me a Solomon Brochure 

I — I Yes, please send a dealer Information packet 

I — I Yes, please send a Reference Manual for 

Solomon (specify series number) 

Check for $65.00 enclosed. (Ohio residents 
add sales tax.) 



Name: 

Title: 

Company: 
Address: _ 
City: 



(State) 



(zip) 



Phone: 



L 



© 



TLB ASSOCIATES, INC. 
1 120 Commerce Parkway 
P.O. Box 414 
Flndlay, Ohio 45840 
(419)424-0422 



MDBS is a trademark of Micro Data Base Sytems. Inc. 
CP/M and PUI-80 are trademarks o! Digital Researcn. Inc. 




1 t^^o^° ti%& 



***** o 



\sc 



SEC 

Microcomputer 

/ /IllllllltllllltlOltnt Hlltlllll»m\\\V.\V\V\ \ 

■7 3a • ij i'i rm i v" 
/;/ SB 'i-'' r-rrrv v v i 




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If you're considering] a compute 

4 Mhz Z-80A Operation 
80 or 40 column modes STANDARD 
Built-in Centronics printer port 
Full ASCII keyboard with Shift lock 
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RGB Color Output 
Mixed text and graphics 
Numerlca Keyboard STANDARD 
CP/M Compatibility 

5 programmable Function keys 

24K Microsoft NBASIC In ROM with enhanced 

color graphic commands 

The NEC PC-800IA has all these features and much 
more. Expandtblllty you want, expandability you get. 
Through the use of the PC-8012A I/O unit, total system 
RAM can be extended to 160K. The PC-8031 Dual Disk 
Drive puts 286K of floppy disk storage at your com- 
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The NEC PC-800IA has so many things that are op- 
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Compare the competition, and then call Consumer 
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NEC COMPATIBLE SOFTWARE 

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1 6K RamBoard by ConComp Industries 130 

Language System w /Pascal & BASICS 379 

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Hayes Micromodem If 299 

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64K Dynamic Ram Board, 200ns $ 499 

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800-854-6654 

In California and 
outside continental U.S. 

(714) 698-8088 

Telex 695-000 Beta CCMO 



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MX-80 



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Ordering information: Phone orders using VISA, MASTERCARD. 
AMERICAN EXPRESS. DINERS CLUB. CARTE BLANCHE, bank 
wire transfer, cashier's or certified check, money order, or personal 
check (allow ten days to clear). Unless prepaid with cash, please add 
5% for shipping, handling and insurance (minimum 5 00) Califor- 
nia residents add 6% sales tax. We accept CODs OEM's. Institutions 
and conporalions please send for a writlen quotation All equipment 
is subject to price change and availability without notice All equip- 
ment Is new and complete with manufacturer's warranty (usually 90 
days! Showroom prices may difler from mail order prices 



Send Orders To: 



g Mailorder 



8314 Parkway Drive 
La Mesa, Calif. 92041 



Circle 104 on inquiry card. 



Listing 4: A disassembly of Color BASIC'S select-joystick subroutine in 6809 machine language. 



Address 


Object Coda 


Source Code 


A9A2 


CE 


FF01 


LDU 


#FF01 


A9A5 


8D 


00 


BSR 


A9A7 


A9A7 


A6 


C4 


LDA 


0,U 


A9A9 


84 


Fl 


ANDA 


#F7 


A9AB 


57 




ASRB 




A9AC 


24 


02 


BCC 


A9B0 


A9AE 


8A 


08 


ORA 


#08 


A9B0 


A7 


CI 


STA 


U+ + 


A9B2 


39 




RTS 





ONCE 



Comments 

$FF01 TO U 
DO $A9A7 TWICE 
READ $FF01 PIA 
RESET SELECT BIT 
SHIFT OUT BIT TO C 
GO IF SELECT BIT = 
SELECT BIT = 1 

STORE IN $FF01 PIA, BUMP TO $FF03 
• RETURN 



Listing 5: A disassembly of Color BASIC'S subroutine to read all four joystick channels in 6809 machine language. 



Address 


Object Code 


Source Code 


A9E0 


8E 


015E 


LDX 


#01 5E 


A9E3 


C6 


03 


LDB 


#03 


A9E5 


86 


0A 


LDA 


#0A 


A9E7 


ED 


E3 


STD 


--S 


A9E9 


8D 


B7 


BSR 


A9A2 


A9EB 


CC 


4080 


LDD 


#4080 


A9EE 


A7 


E2 


STA 


-S 


A9F0 


CA 


02 


ORB 


#02 


A9F2 


F7 


FF20 


STB 


FF20 


A9F5 


C8 


02 


EORB 


#02 


A9F7 


B6 


FF00 


LDA 


FF00 


A9FA 


2B 


03 


BMI 


A9FF 


A9FC 


E0 


E4 


SUBB 


0,S 


A9FE 


8C 


EBE4 


CMPX 


#EBE4 


AA01 


A6 


E0 


LDA 


S + 


AA03 


44 




LSRA 




AA04 


81 


01 


CMPA 


#01 


AA06 
AA08 
AA09 


26 
54 
54 


E6 


BNE 

LSRB 

LSRB 


A9EE 


AA0A 


El 


IF 


CMPB 


-01, X 


AA0C 


27 


04 


BEQ 


AA12 


AA0E 


6A 


E4 


DEC 


0,S 


AA10 


26 


D9 


BNE 


A9EB 


AA12 


E7 


82 


STB 


-X 


AA14 


EC 


El 


LDD 


S+ + 


AA16 


5A 




DECB 




AA17 


2A 


CC 


BPL 


A9E5 


AA19 


39 




RTS 




>> 











Comments 



POINT TO STORAGE + 1 
LOOP COUNT-3 TO 
► # OF RETRIES 

SAVE # TIMES, RETRIES 
SELECT JOYSTICK 3-0 
— ** $40-A,$80-B = DELTA, START 
►SAVE 

??RS-232 OUT 

CURRENT TRY TO D/A 

FLIP BIT? 

GET JOYIN 

GO IF 1 

SUBTRACT DELTA 

BYTES 2,3 = ADDB0,S 

GET DELTA 

FIND NEXT DELTA 

TEST FOR END 
GO IF NOT DELTA OF 1 



ALIGN FINAL VALUE TO 00XXXXXX 

GET LAST VALUE 
GO IF EQUAL 
NOT EQUAL— RETRY 
-TRY 10 TIMES 



STORE VALUE IN STORAGE 
GET COUNT 
DECREMENT COUNT(#) 
-GO IF NOT 4 JOYSTICKS 



RETURN 



security systems. 

• A spring-loaded, sliding potentio- 
meter (which costs a few dollars) 
could be used with a second resistor 
to provide an output for a scale to 
weigh anything from elephants to 
letters. 

• The same device can be used to con- 
vert linear movement into a form 
readable by the Color Computer. 
With two multi-turn potentiometers 
(under $10 each), a little bit of cord, 
and a few pulleys, it's not difficult to 
construct an X/Y plotter to enable 



manual digitization of two-dimen- 
sional drawings or patterns. 

• With a photocell, a simple lens (for 
example, a partial microscope assem- 
bly), and some transistor amplifica- 
tion, it's possible to construct an 
automatic digitizer that will convert 
shades of gray into digital form for 
screen display. 

• Remove the stops from a linear- 
taper potentiometer (not hard to do) 
and you have a resistor whose resis- 
tance value is an analog of compass 
heading or rotational position. Use 



this with a second resistor as in the 
voltage-divider circuit discussed 
above (figures 7 and 8). 

Well, I hope you're impressed with 
the possible uses of the Color Com- 
puter's A/D circuitry. It's not that 
difficult to devise real-world "sen- 
sors," and it's fun to write the soft- 
ware that drives them. Once you 
have started, you'll find that the pos- 
sibilities are endless. Just think what 
Rube Goldberg could have done with 
a Color Computer! ■ 



158 December 1981 © BYTE Publications Inc 



Circle 357 on inquiry card. 



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Commentary on the Machine- Language Subroutines 



Select-Joystick. On entry to the 
select-joystick subroutine, load the B 
register with the joystick channel num- 
ber 0-3. The user stack pointer register 
U is first loaded with $FF01. A follow- 
ing BSR $A9A7 performs the subrou- 
tine code twice. A is first loaded with 
the current configuration of the PIA 
bits at address $FF01. An AND with 
$F7 resets the select bits. The ASRB 
shifts the least-significant bit of the B 
register into the carry flag. If this bit is 
a 1, an OR with 8 sets the select bit. 
The STA U+ + stores SEL2 and incre- 
ments the user stack pointer by two so 
that it holds $FF03. The RTS returns to 
$A9A7, where the same operation is 
repeated for the second select bit in the 
PIA at address $FF03. 

Read-Joystick. The main code for 
the joysticks is at $A9E0 (see listing 5). 
This code is entered without param- 
eters and stores the values of channels 
through 3 into page-zero locations 
$15A, $15B, $15C, and $15D. 

The X index register initially points 
to the address following the joystick 
variable storage location. B is loaded 
with a loop count of 3. The code from 
$A9E5 through $AA17 is the outer 
loop. For each of four passes, a chan- 
nel value is found and put into a joy- 
stick variable. 

Outer loop: A is loaded with $0A 
(decimal 10). This is the number of 
retries for the joystick value. If the 
same value is not found a second time, 
up to 10 tries are made to find a match- 



ing value. The number of times in B 
and the number of retries is stored in 
the stack by the STD instruction. A 
call, is then made to $A9A2 to select the 
current joystick channel. This corre- 
sponds to the loop count of 3 to in B. 
The code from $A9EB through $AA10 
is inner loop 1. It finds the value of the 
channel. At the end of this loop 
($AA12), the value is stored in the 
variable storage area by STB — X. 
This auto-decrement causes X to point 
to the next lower value before the store 
occurs. Next, the count in B and the 
number of retries in A are retrieved by 
the LDD, the count is decremented, 
and a BPL causes a loop back to $A9E5 
if the count is not equal to —1. 

Inner loop 1: The code from $A9EB 
through $AA10 is the inner loop that 
finds the value for the current channel. 
Within this code is inner loop 2, from 
$A9EE through $AA06, which actually 
does the binary search. The value $40 
is loaded into A and the value $80 into 
B to start the search. Value $80 is 
binary lOOOOOxx for the initial value of 
32, while value $40 contains binary 
OlOOOOxjc for the "delta," the size of the 
remaining range. 

At the end of the binary search at 
$AA08, the final PIA-format value is 
in B. This value is aligned to the right 
by the two LSRBs to represent a binary 
value of through 63. It is then com- 
pared with the previous value. If these 
are the same, a branch is made to 
$AA12 to store the value in the outer 



loop. If the value is different, the 
number of retries is decremented, and, 
if the count is not equal to 0, another 
binary search is done by a branch to 
$A9EB. 

Inner loop 2: The code from $A9EE 
through $AA06 is the binary search to 
find the channel value. A (the delta) is 
saved in the stack. The current value in 
B is then output to the DAC by STB 
$FF20. The output of the comparator is 
read by the LDA $FF00. If this value is 
equal to 1, the delta is added to the cur- 
rent value; if it is equal to 0, the delta is 
subtracted from the current value. The 
next value is then found by retrieving 
the delta from the stack and shifting it 
right one bit position. If the result is 1, 
the smallest delta has been processed, 
and B holds the final value. If the next 
delta is not 1, a branch back to $A9EE 
goes to the next iteration in the search. 

This subroutine can be used for 
high-speed processing of the joystick 
position from other assembly-language 
programs. Results are obtained 
quickest when the joystick position is 
fixed and only one retry is necessary 
for comparison. A test program from 
BASIC indicates that it takes about 1.5 
milliseconds for each set of four 
values. To find only the X channel of 
joystick 0, call location $A9E5 with 
B = and X pointing to $15A. In this 
case, the time should be about 400 
microseconds, although I haven't 
verified this. 




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160 December 1981 © BYTE Publications Inc 



Circle 114 on inquiry card. 



Circle 425 on inquiry card. 



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Verbatim Datalife- flexible disks, 
(he best thing you can do for 
your computer or word processor 
is to keep it running clean and 
error-free. 

And the way to do just that 
is with Verbatim's hew Datalife 
1 lead Cleaning Kit. It can remove 
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performance. 

Quick and easy to use 

All you have to do is remove a 
Cleaning Disk from its protective 
pouch, put the disk in the spec- 
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and turn it on. 



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Cleaning, 
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With your Datalife Head Clean- 
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applying solvents that can splash 
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What's more, with Datalife 
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There's no worry about damaging 
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Protect your investment 

The Datalife Head Cleaning Kit 
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system performance because of 
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So if you want your data 
back verbatim, keep it on Verbatim 
disks. And keep your disk drives 
clean with Verbatim's Datalife Head 
Cleaning Kit. 

Call (800) 538-1793 for 
the name of your nearest Verbatim 
dealer. (In California and outside 
the U.S. call (408) 737-7771 
collect.) 



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162 BYTE Derambtr 1981 



Circle 214 on inquiry card. 




ttle of the Asteroids 



Gregg Williams, Senior Editor 




1 : Planetoids, from Adventure International; 2: Super Nova, from Big Five Software; 3: Apple-oids, f ram Califor- 
nia Pacific Computer Co; A: The Asteroid Field, from Cavalier Computer; 5; Meteoroids in Space, from Quality 
Software; B; Bubbles, from Softape; "7: Planetoids, from Softape; B: Asteron, from Western MicnoOata 
Enterprises, Ltd. 



If imitation is the sincerest form of flattery, then the 
people who designed Atari's coin-operated video game 
Asteroids have a lot to be proud of. Asteroids is one of 
the most successful commercial games around (equaled 
or surpassed only by Midway's Space Invaders and a 
newer Atari game, Missile Command) and has its own se- 
quel (Asteroids Deluxe, also by Atari). Its popularity has 
inspired numerous imitations for use with personal com- 
puters. With so many versions around, the only dilemma 
is which one to buy. 

I gathered every Asteroids-like game I could find (all 
but one were for the Apple II) and created a chart that 
shows you which version does what. Some notes to keep 
in mind: all Apple disk versions boot on either DOS 3.2 
or 3.3 systems; unless noted in the table, versions with 
sound have no way of turning it off (important when 
playing late at night); all the games (except Apple-oids) 



give a black-and-white-only display; all of the versions 
are, in their own way, entertaining and well done; and 
none of the games (except possibly The Asteroid Field) 
looks or works exactly like the arcade original. Also keep 
in mind that two of these Asteroids-like games (Apple- 
oids and Bubbles/Planetoids) give you an extra game in 
the package price; this certainly influences how much 
game you get for your money. ■ 

See pages 164-165 for the comparison chart. 



Asteroids is a trademark of Atari, Inc. The game is 
available in two coin-operated versions and cartridges 
for the Atari Video Computer System (game-cartridge 
system) and the Atari Personal Computer System (the 
Atari 400 and 800 microcomputers). 



December 1981 © BYTE Publications lnc 



163 



Product 
Name 


Manufacturer 


Price 


Computer Used 


Levels of Play 


Ships per 
Game 


Method 
of Firing 


Planetoids 


Adventure International 
POB 3435 
Longwood FL 32750 


$19.95 
(disk), 
$14.95 
(cassette 
that loads 
to disk) 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


three: easy 
(asteroids ex- 
plode each 
other), regular, 
hard (asteroids 
attracted to 
ship) 


four 


any key 


Super Nova 


Big Five Software 

POB 9078-185 

Van Nuys CA 91409 


$17.95 
(Model I 
disk ver- 
sion), 
$15.95 
(Model l/lll 
cassette 
version) 


Radio Shack 
TRS-80 Model I or 
III (disk and 32 K 
bytes of memory 
for disk version, 
16 K bytes of 
memory for 
cassette version) 


one 


three 


P key 


Apple-oids 
(part of 
Apple-oids 
game package) 


California Pacific 
Computer Co 
1623 Fifth St 
Davis CA 95616 


$29.95 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


one 


three 


through 
9 keys 
(identical 
in func- 
tion) 


The Asteroid 
Field 


Cavalier Computer 

POB 2032 

Del Mar CA 92014 


$24.95 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


two 


Five (easy 
level of 
play) or 
three (ex- 
pert level) 


several: 

forward 

arrow, 

paddle 

button 

or 1; see 

notes 


Meteoroids in 
Space 


Quality Software 
6660 Reseda Blvd 
Suite 105 
Reseda CA 91335 


$19.95 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


one (but 
many variations 
influence diffi- 
culty) 


five 


autofire 
(bursts of 
fire come 
automat- 
ically 
from ship) 
or space 
bar for 















firing 


Bubbles (part 
of Baker's 
Trilogy) 


Softape 

10432 Burbank Blvd 

North Hollywood CA 91601 


$29.95 for 
a disk 

containing 

Bubbles, 

Planetoids, 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


one 


three 


paddle 
button 






and a rac- 
ing game 
called 
Burnout 










Planetoids (part 
of Baker's 
Trilogy) 


Softape 

10432 Burbank Blvd 

North Hollywood CA 91601 


$29.95 for 
a disk 
containing 
Bubbles, 
Planetoids, 
and a rac- 
ing game 
called 
Burnout 


Apple II or II Plus 
with 32 K bytes of 
memory and one 
disk drive 


one 


three 


ship fires 
automati- 
cally dur- 
ing game 
(no player 
control 
over firing 

















Asteron 



Western MicroData 

Enterprises Ltd. 
POB G33 
Postal Station G 
Calgary, Alberta T3A 2G1 
Canada 



$29.95 



Apple II or II Plus 
with 48 K bytes of 
memory and one 
disk drive 



three 



space bar 



164 



December 1981 © BYTE Publications Inc 







Hyper- 










Method of 


Method of 


space 




Number and 






Turning 


Moving 


Avail- 


Sound 


Kind of 




Overall 


Ship 


Ship 


able? 


Effects? 


Enemy Ships 


Notes 


Impression 


paddle 


paddle button 


no 


yes 


two kinds of 


• See May 1981 


• An interesting 




causes 






enemy ships 


BYTE, page 116, for 


Asteroids-like game. 




movement 






that shoot back 


a full review. 






until button 








•Hard level 






released 








of play is too 
hard— ships get 
destroyed as soon 
as they appear. 




T and R keys, 


key causes 


yes 


no 


five kinds of 


•See May 1981 


•The best TRS-80 


to rotate ship 


movement 


(space 




enemy ships 


BYTE, page 108, for 


Asteroids-like game 


one-eighth 


until key 


bar) 




that shoot back 


a full review. 


I've seen. 


turn clock- 


released 






(with varying 






wise and 








degrees of 






counter- 








intelli- 






clockwise, 








gence) 






respectively 














paddle 1 


paddle button 


yes (any 


yes 


two kinds of 


•A nice feature is 


•A good version of 




1 causes 


key ex- 




enemy ships 


that your ship 


Asteroids (but the 




movement 


cept 




that shoot back 


rotates three com- 


asteroids are shaped 




until button 


through 9) 




(enemy ships 


plete turns for the 


like apples- 




released 






are colored 
yellow) 


full paddle move- 
ment; this prevents 
rotation problems 
when you are near 
the end of the pad- 
dle rotation. 


strange!) 

•Includes a Break- 
out-like game that is 
also very good. 

•A nice set of 
games for the price. 


several: D 


several: back 


yes 


yes (in- 


two kinds of 


• Game gives four 


• Many options 


and F keys, 


arrow, paddle 


(space 


cluding an 


enemy ships 


options for ship con- 


make this game very 


paddle 0; see 


button 1; see 


bar); 


acceler- 


that shoot back 


trol: one keyboard- 


easy to play. 


notes 


notes 


screen 


ating 


(size and shape 


only option and 


• Display is flicker- 






flashes to 


"thump- 


same as in 


three that use key- 


free. 






denote 


thump" 


coin-operated 


board and/or 


•Game play is 






hyper- 


sound as 


game) 


paddles. 


closest to coin- 






space 


found in 




•Sound effects 


operated version of 






jump— 


Space In- 




cannot be turned off. 


all versions listed 






a nice 


vaders) 




• Control-C inverts 


here. 






touch 






playfield to black 
on white. 


• Easily the best 
Apple Asteroids-like 
game I've seen. 


P, RETURN 


Z key or pad- 


yes 


yes (in- 


one kind of 


•An updated ver- 


• A very good 


keys (manual 


dle button 0; 


(asterisk 


cluding an 


ship that 


sion of Asteroids in 


Asteroids-like game 


turn), arrow 


ship can use 


key) 


acceler- 


shoots back 


Space (reviewed on 


(although it is not 


keys (auto- 


"auto brake" 




ating 


(and is very ac- 


page 116 of the May 


exactly like the 


matic turn), or 


(moving ship 




"thock- 


curate) 


1981 BYTE). 


original). 


paddle 


does not 




thock" 




• Good placement 


•Game has five 




coast indefi- 




sound as 




of keys for key- 


sets of options; dif- 




nitely) or not 




found in 
Space In- 
vaders) 




board version. 


ferent combinations 
give several levels of 
difficulty. 


paddle 


none; hexa- 
gonal ship is 
fixed in 
center of 
screen 


no 


yes 


no enemy ships 


• Bubbles bounce 
back from the top 
and bottom edges 
of the screen. 

•Smallest bubbles 
are very small but 
still dangerous. 


• An interesting 
variation of 
Asteroids. 


paddle 


paddle button 


yes (any 


yes 


no enemy ships 


•Planetoids are 


•An interesting 




causes 


key) 






pentagons that 


variation of 




movement 








come in four sizes. 


Asteroids. 




that con- 








•Game gives 






tinues until 








extra points for 






an opposite 








"docking" (running 






thrust is 








over) with "stars" 






applied 








that decrease in size 
and vanish. 




paddle or 


button on paddle 


yes (hit 


yes; may 


one kind of 


• All figures on the 


•A mediocre im- 


Q,U,W,I.E,0, 


(or C and 


any num- 


be turned 


enemy ship 


screen flicker 


plementation; it is 


R,P keys 


M keys) 


ber key) 


on and off 


that shoots 


slightly. 


awkward to use and 




causes move- 




with con- 


back 


• Player must hit S 


has no interesting 




ment that 




trol-Q 




key with each new 


features to com- 




continues un- 








ship to start (or re- 


pensate. 




til an oppo- 








start) game. 






site thrust is 














applied 













December 1981 © BYTE Publications lnc 165 



The Atari Tutorial 

Part 4: Display-List Interrupts 



Chris Crawford 

1272 Borregas Ave 

Sunnyvale CA 94086 



The display-list interrupt is one of 
the most powerful features built into 
the Atari personal computer system. 
It is also one of the least accessible 
features of the system, requiring of 
the programmer a firm understanding 
of assembly language as well as all of 
the other characteristics of the 
machine. Used alone, display-list in- 
terrupts provide no additional 
capabilities; they must be used in con- 
junction with the other features of the 
system, such as player-missile 
graphics, character-set indirection, or 
color-register indirection. With 
display-list interrupts, the full power 
of these features can be realized. 

Display-list interrupts take advan- 
tage of the sequential nature of the 
raster-scan television display. The 
television draws the screen image in a 
time sequence, from the top of the 
screen to the bottom. This drawing 
process takes about 13,000 micro- 
seconds and looks instantaneous to 
the human eye. But that is a long time 
in comparison to the time scale the 
computer works in. The computer 
has plenty of time to change the 
parameters of the screen display 

This article appears in slightly different 
form in De Re Atari, a book published by 
Atari Inc, and is reproduced with its ex- 
press permission. 



while it is being drawn. Of course, 
the computer must make each change 
each time the screen is drawn, which 
happens 60 times per second. Also 
(and this is the tricky part), it must 
change the parameter in question at 
exactly the same moment each time 
the screen is drawn. That is, the cycle 
of changing screen parameters must 
be synchronized to the screen- 
drawing cycle. One way to do this 
might be to lock the 6502 micro- 



With display-list 

interrupts, many key 

Atari registers can be 

changed during the 

drawing of a single 

screen-display frame. 



processor into a tight timing loop 
with an execution frequency of exact- 
ly 60 hertz. This would make it very 
difficult for the computer to do 
anything other than the screen- 
display computations. It would also 
be a tedious job. A much better way 
is to interrupt the 6502 just before the 
time has come to change the screen 
parameters. The 6502 responds to the 
interrupt, changes the screen 
parameters, and returns to its normal 



business. The interrupt to do this 
must be precisely timed to occur at 
exactly the same point during the 
screen-drawing process. This spe- 
cially timed interrupt is provided by 
the ANTIC integrated circuit within 
the Atari 400/800; it is called a 
display-list interrupt (DLI). 

The timing and execution of any in- 
terrupt process can be intricate; there- 
fore, I shall first describe the sequence 
of events in a properly working 
display-list interrupt. The process 
begins when the ANTIC chip en- 
counters a display-list instruction 
having its interrupt bit (bit D7) set. 
ANTIC waits until the last scan line 
of the mode line it is currently 
displaying. ANTIC then refers to its 
NMIEN (nonmaskable interrupt 
enable) register (hexadecimal location 
D40E) to see if display-list interrupts 
have been enabled. If the enable bit 
(bit D7) is cleared (to a logic 0), AN- 
TIC ignores the interrupt and con- 
tinues its regular tasks. If the enable 
bit is set (to a logic 1), ANTIC "pulls 
down" the NMI (nonmaskable inter- 
rupt) line on the 6502, signaling an 
interrupt. ANTIC then goes back to 
its normal display activities. The 6502 
starts executing an interrupt-service 
routine pointed to by the NMI vector 
in the operating system. This routine 
first determines the cause of the inter- 



166 December 1981 © BYTE Publications Inc 



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rupt. If the interrupt is indeed a 
display-list interrupt, control is 
transferred indirectly by means of the 
16-bit address contained in hexa- 
decimal locations 0200 and 0201 (low 
byte first) to a DLI-service routine. 
The DLI routine changes one or more 
of the graphics registers controlling 
the display. The 6502 then returns 
from the interrupt routine to resume 
its mainline program. 

Creating a Display-List Interrupt 

A number of steps are involved in 
setting up a display-list interrupt. The 



first thing you must do is write the 
DLI routine itself. The routine must 
start by pushing any 6502 registers 
that will be altered onto the stack, 
because the operating system 
interrupt-poll routine itself saves no 
registers. (The 6502 status register is 
automatically pushed onto the stack.) 
The routine should be short and fast; 
it should change only those registers 
related to the display; and it should 
end by restoring any 6502 registers 
pushed onto the stack. 

Next, you must place the DLI- 
service routine somewhere in 



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memory. Page six (hexadecimal ad- 
dresses 600 to 6FF) is an ideal place. 
Set the vector at hexadecimal loca- 
tions 0200 and 0201 to point to your 
routine. Determine the vertical point 
on the screen where you want the DLI 
to occur, and then go to the cor- 
responding display-list instruction 
and set bit D7 of the previous instruc- 
tion. Finally, enable the DLI by set- 
ting bit D7 of the NMIEN register at 
hexadecimal location D40E. The DLI 
will begin executing immediately. 

As with any interrupt-service 
routine, timing considerations can be 
critical. ANTIC does not send the in- 
terrupt to the 6502 immediately upon 
encountering an interrupt instruction; 
it delays doing this until the last scan 
line of the interrupting mode line. 
The 6502 and the interrupt-service 
routine in the operating system 
together consume 33 machine cycles. 
Thus, the first instruction of your 
DLI-service routine will not be 
reached until 33 machine cycles have 
elapsed in the last scan line of the in- 
terrupting mode line. Thirty-three 
machine cycles corresponds to 66 
color clocks on the screen. Thus, 
your DLI-service routine will begin 
executing while the electron beam is 
partway across the screen in the last 
scan line of the interrupting mode 
line. For example, if such a DLI 
routine changes a color register, the 
old color will be displayed on the left 
half of the scan line and the new color 
will show up on the right half of the 
same scan line. Because of uncertain 
timing in the response of the 6502 to 
an interrupt, the border between the 
colors will not be sharp, but will 
jiggle back and forth irritatingly. 

The solution to this problem is pro- 
vided in the form of the WSYNC 
(wait for horizontal sync) register 
(hexadecimal address D40A). When- 
ever this register is addressed in any 
way, the ANTIC chip pulls down the 
RDY line on the 6502. This effectively 
halts the 6502 until the WSYNC 
register is reset by the next horizontal 
synch pulse. The result is that the 
6502 freezes until the electron beam 
returns to the left edge of the screen. 
If you insert a STA WSYNC instruc- 
tion just before an instruction that 
stores a value into a color register, the 
color being displayed will change 



170 December 1981 © BYTE Publications Inc 



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Listing 1: A simple Atari BASIC program to demonstrate display-list interrupts. This program changes the screen color from blue 
to pink and darkens the character set halfway down the video display. The complete BASIC program in listing la contains the 
assembly-language routine given in listing lb. 



la 

10 DLIST=PEEK(560)+256*PEEK(561):REM 

20 POKE DLIST+15,130:REM 

30 FOR l=0 TO 19: REM 

40 READ A:POKE 1536+1 ,A:NEXT I 

50 DATA 72,138,72,169,80,162,88 

60 DATA 141,10,212,141,23,208 

70 DATA 141,24,208,104,170,104,64 

80 POKE 512,0:POKE 513,6:REM 

90 POKE 54286,1 92: REM 



find display list 

insert interrupt Instruction 

loop for poking DLI service routine 



poke In Interrupt vector 
enable DLI 



ib 

PHA 

TXA 



save accumu I ator 



PHA save X-reglster 

LDA #$50 dark color for characters 

LDX #$58 pink 

STA WSYNC wait 

STA C0LPF1 store color 

STX C0LPF2 store color 

PLA 



PLA 


restore registers 


RTI 


done 



while the beam is off the left edge of 
the screen. The color transition will 
occur one scan line lower, but it will 
be neat and clean. 

The proper way to use a display- 
list interrupt, then, is to set the DLI 
bit on the mode line before the mode 
line for which you want the action to 
occur. The DLI-service routine 
should first save the 6502 registers 
onto the stack and then load the 6502 
registers with -the new graphics values 
to be used. It should execute a STA 
WSYNC immediately before storing 
the new values into the appropriate 
ANTIC or CTIA registers. Finally, it 
should restore the 6502 registers and 
return from the interrupt. This pro- 
cedure will guarantee that the 
graphics registers are changed while 
the electronic beam is off the screen 
and that the new display parameters 
take effect at the beginning of the 
desired line. 

The program in listing 1 is a very 
simple DLI-service routine. It changes 
the background color from blue to 
pink. It also changes the color of the 
characters so that they show up as 
dark against the pink background. 
The upper half of the screen remains 



172 December 1981 © BYTE Publications Inc 




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blue even though the DLI routine 
keeps stuffing pink into the color 
register. This is because the operating 
system's vertical-blank-interrupt 
routine keeps stuffing blue into the 
color register during the vertical- 
blank period. The blue color comes 
from the operating system's shadow 
register for that color register. Every 
hardware color register is shadowed 
out to a RAM (random-access 
read/write memory) location. You 
may already know about these 
shadow registers at decimal locations 
708 through 712. For most purposes, 
you can change colors by poking 
values into the shadow registers (see 
last month's article for an explanation 
Of shadow registers). If you poke 
directly into the hardware registers, 
the operating system shadow process 
will wipe out your poked color within 
y 60 second (ie: at the top of a new 
screen display). For DLIs, however, 
you must store your new color values 
directly into the hardware registers. 
You cannot use a DLI to set the color 
of the first displayed line of the 
screen. The operating system takes 
care of that line for you (and the first 
line is off the top of the screen, 



Listing 2: Restoring the Atari attract 
mode to a display driven by display-list 
interrupts. Only two 6502 assembly- 
language instructions have to be added to 
the DLI routine. DRKMSK and COLRSH 
are page zero locations (hexadecimal 4E 
and 4F) set up and updated by the 
operating system during the vertical blank 
interrupt. When the attract mode is not in 
force, COLRSH takes a value of 00 and 
DRKMSK takes a value of hexadecimal 
FF. When attract mode is in force, 
COLRSH is given a new random value 
every four seconds and DRKMSK holds a 
value of hexadecimal F6. Thus, COLRSH 
scrambles the color and DRKMSK lops 
off the high-order luminance bit. 

LDA NEWCOL LDA NEWCOL 

STA WSYNC EOR COLRSH 

STA C0LPF2 AND DRKMSK 

STA WSYNC 

STA C0LPF2 



anyway). Use DLIs to change colors 
of lines below the first line. 

By stuffing colors directly into the 
hardware registers, you create a new 
problem: you defeat the automatic 
attract mode. Attract mode is a 
feature provided by the operating 
system. After nine minutes without a 
keypress, the colors on the screen 
begin to cycle through random hues 
at lowered luminances. This insures 
that a computer left unattended for 
several hours does not burn an image 
into the television screen. 

It is easy to build attract mode into 
a DLI routine by inserting only two 
lines of assembly code, as shown in 
listing 2. 

The implementation of attract 
mode in display-list interrupts exacer- 
bates an already difficult problem: 
the shortage of execution time during 
a DLI. A description of DLI timing 
will make the problem more obvious. 

DLI Timing 

DLI execution is broken into three 
phases. Phase 1 covers the period 
from the beginning of the DLI to the 
STA WSYNC instruction. During 
phase 1, the electron beam is drawing 
the last scan line of the interrupting 
mode line. Phase 2 covers the period 
from the STA WSYNC instruction to 
the appearance of the beam on the 
television screen. Phase 2 cor- 
responds to the horizontal blank; all 
graphics changes should be made dur- 
ing this phase. Phase 3 covers the 
period from the appearance of the 
beam on the screen to the end of the 
DLI-service routine. The timing of 
phase 3 is not critical. 

One horizontal scan line takes 114 
clock cycles of real time. A DLI 
reaches the 6502 on or around cycle 
number 15. The 6502 takes about 7 
cycles to respond to the interrupt. 
The operating-system routine to ser- 
vice the interrupt and turn control 
over to the DLI-service routine takes 
11 machine cycles. Thus, the DLI- 
service routine does not gain control 
until about 33 clock cycles have 
elapsed. Furthermore, the STA 
WSYNC instruction must begin by 
cycle number 103; this reduces the 
time available in phase 1 by 11 cycles. 
Finally, ANTIC's DMA (direct 
memory access) will steal some of the 



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remaining clock cycles from the 6502. 
Nine cycles will be lost to memory- 
refresh DMA. This leaves an absolute 
maximum of 61 cycles available for 
phase 1. This maximum is achieved 
only with blank-line mode lines. 
Character and map mode instructions 
will result in the loss of one cycle for 
each byte of display data. The worst 
case arises with BASIC modes 0, 7, 
and 8, which require 40 bytes per 
line. Only 21 machine cycles are 
available to phase 1 in these modes. 
Thus, a phase 1 routine will have 
from 21 to 61 machine cycles of 
execution time available to it. 

Phase 2, the critical phase, extends 
over 24 clock cycles of real time. As 
with phase 1, some of these cycles are 
lost to cycle-stealing DMA. Player- 
missile graphics will cost 5 cycles if 
they are used. The display instruction 
will cost 1 cycle. Two more cycles 
will be stolen if the Load Memory 
Scan option in the display list is used. 
Finally, 1 or 2 cycles may be lost to 
memory refresh or display-data 
retrieval. Thus, from 14 to 23 



usable machine cycles are available to 
phase 2. 

The problems of DLI timing now 
become obvious. To load, attract, 
and store a single color will consume 
14 cycles. Saving the 6502 A, X, and 
Y registers onto the stack and then 
loading, attracting, and saving three 
colors into A, X, and Y registers will 
cost 47 cycles: most, if not all, of 
phase 1. Obviously, the programmer 
who wishes to use DLIs for extensive 
graphics changes will expend much 
effort on the timing of the DLI. For- 
tunately, the beginning programmer 
need not concern himself with exten- 
sive timing calculations. If only 
single-color changes or simple 
graphics operations are to be per- 
formed, cycle counting and speed op- 
timization are unnecessary. These 
considerations are only important for 
high-performance situations. 

No simple options are available to 
the programmer who needs to change 
more than three color registers in a 
single DLI. It might be possible to 
load, attract, and store a fourth color 



early in phase 3, if that color is not 
displayed on the left edge of the 
screen. Similarly, a color not showing 
up on the right side of the screen 
could be changed during phase 1. 
Another approach is to break one 
overactive DLI into two less am- 
bitious DLIs, each doing half the 
work of the original. The second DLI 
could be provided by inserting a 
single-scan-line blank instruction 
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list just below the main interrupting 
mode line. This will, of course, con- 
sume some screen space. 

Another partial solution is to per- 
form the attract chores during 
vertical-blank periods. To do this, 
two tables of colors must be kept in 
memory. The first table contains 
color values intended to be displayed 
by the DLI routines. The second table 
contains the attracted values of these 
colors. During vertical blank, a user- 
supplied interrupt-service routine 
fetches each color from the first table, 
attracts it, and stores the attracted 
color in the second table. The DLI 



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176 December 1981 © BYTE Publications Inc 



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18 LOAD SALES TAX TABLE 

19 UPDATE SYSTEM FILE 

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EJ EXIT FROM SYSTEM 



PLEASE ENTER FUNCTION NUMBER 



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Listing 3a: An assembly-language routine which is included in the multiple display-list- 
interrupt program shown in listing 3b. 

PHA 

TXA 

PHA 

INC COUNTR 

LDX COUNTR 

LDA COLTAB,X use page $FO for color table 

STA WSYNC wait 



STA COLBAK 
CPX #$4F 
BNE ENDDLI 
LDA #$00 
STA COUNTR 
ENDDLI FLA 
TAX 
PLA 
RTI 



I ast I i ne? 

no, exit 

yes, reset counter 



restore accumulator 



routine then retrieves values directly 
from the second table without paying 
the time penalty for attract. 

Multiple Display-List Interrupts 

It is often desirable to have a 
number of DLIs occurring at several 
vertical positions on the screen. This 
is an important way to add color to a 
display. Unfortunately, there is only 
one DLI vector; if multiple DLIs are 
to be used, then the vectoring to the 
appropriate DLI must be imple- 
mented in the DLI routine itself. 
There are several ways to do this. If 
the DLI routine does the same process 
with different values, then it can be 
table-driven. On each pass through 
the DLI routine, a counter is incre- 



mented and used as an index to a 
table of values. A sample DLI routine 
for doing this is given in listing 3. 

Another way to implement multi- 
ple display-list interrupts is to use a 
DLI counter as a test for branching 
through the DLI-service routines to 
the proper DLI-service routine. This 
slows down the response of all the 
DLIs, particularly the ones at the end 
of the test sequence. A third method 
is to have each DLI-service routine 
write the address of the next routine 
into the DLI vector at hexadecimal 
locations 200 and 201. This should be 
done during phase 3. It is the most 
general solution to the problem of 
multiple DLIs and has the additional 
advantage that vectoring logic is per- 



180 December 1981 © BYTE Publications Inc 



Listing 3b: A simple Atari BASIC program to demonstrate multiple display-list interrupts. This program puts 80 different colors on 
the video display. The complete BASIC program shown here contains the assembly-language routine given in listing 3a. 



find display I 1st 

give every mode line a DLI 

BASIC mode 7 with DLI bit set 



10 GRAPHICS 7 

20 DL I ST=PEEK(560)+256*PEEK( 561 ) : REM 

30 FOR J =6 TO 84: REM 

40 POKE DLIST+J,141:REM 

50 NEXT J 

60 FOR J=0 TO 30 

70 READ A: POKE 1536+ J, A: NEXT J: REM poke In DLI service routine 

80 DATA 72,138,72,238,32,6,175,32,6 

90 DATA 189,0,240,141,10,212,141,26,208 

100 DATA 224,79,208,5,169,0 

110 DATA 141,32,6,104,170,104,64 

120 POKE 512,0:P0KE 513,6:REM vector to DLI service routine 

130 POKE 54286, 192: REM enable DLI 



formed after the time-critical portion 
of the DLI, not before. 

Keyboard-Click Routine 

The operating system keyboard- 
click routine interferes with the func- 
tion of the DLI. Whenever a key is 
pressed and acknowledged, the on- 
board speaker is clicked. The timing 
for this click is provided by several 
STA WSYNC instructions. This can 
throw off the timing of a DLI routine 
and cause the screen colors to jump 
downward by one scan line for a frac- 
tion of a second. There is no easy 
solution to this problem. One pos- 
sible remedy involves the VCOUNT 
register (hexadecimal location D40B), 
a read-only register in ANTIC that 
tells what scan line ANTIC is display- 
ing. A DLI routine could examine this 
register to decide when to change a 
color. Another solution is to disable 
the operating system keyboard- 
service routine (a tedious job) and 
provide your own keyboard routine. 
A third alternative is to accept no in- 



puts from the keyboard. If keypresses 
are not acknowledged, the screen 
jiggle does not occur. 

Kernels 

The display-list interrupt was 
designed to replace a more primitive 
software/hardware technique called a 
kernel. A kernel is a 6502 program 
loop that is precisely timed to the 
display cycle of a television set. By 
monitoring the VCOUNT register 
and consulting a table of screen 
changes catalogued as a function of 
VCOUNT values, the 6502 can arbi- 
trarily control all graphics values for 
the entire screen. A high price is paid 
for this power: the 6502 is not 
available for computations during the 
screen-display period, which is about 
75 percent of the time. Furthermore, 
no computation may consume more 
than the 4000 or so machine cycles 
available during vertical-blank and 
overscan periods. This restriction 
means that kernels can only be used 
with programs requiring little com- 



putation, such as certain skill and 
action games. For example, the 
Basketball program for the Atari 
400/800 uses a kernel; the program 
requires little computation but much 
color. The multicolored players in 
this game could not be done with 
display-list interrupts because DLIs 
are keyed to playfield vertical posi- 
tions, not player positions. 

It is possible to extend the kernel 
idea right into a single scan line and 
change graphics registers on the fly. 
In this way, a single color register can 
present several colors on a single scan 
line. The horizontal position of the 
color change is determined by the 
amount of time that elapses before 
the change goes in. Thus, by carefully 
counting machine cycles you can get 
more graphics onto the screen. Unfor- 
tunately, this is extremely difficult to 
achieve in practice. With ANTIC per- 
forming DMA on the 6502, it is very 
difficult to know exactly how many 
cycles have really elapsed; a simple 
count of 6502 cycles is not adequate. 



December 1981 © BVTE Publications Ire 181 



Circle 31 on inquiry card 







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If ANTIC's DMA is turned off, the 
6502 can assume full control of the 
display, but it must then perform all 
the work that ANTIC normally does. 
For these reasons, horizontal kernels 
are seldom worth the effort. If the 
two images to be displayed in dif- 
ferent colors are widely separated, 
however, say by 20 color clocks or 
more, the separation should cover up 
the timing uncertainties and render 
this technique feasible. 

Using Display-List Interrupts 

The tremendous value of graphics 
indirection and all those modifiable 
registers in the hardware now 
becomes obvious. With display-list 
interrupts, every one of those 
registers can be changed dynamically. 
You can put lots of color, graphics, 
and special effects onto the screen. 
The most obvious application of DLIs 
is to put more color onto the screen. 
Each color register can be changed as 
many times as you have DLIs. This 
applies to both playfield color 
registers and player color registers. 
Thus, you have up to nine color 
registers, each of which can display 
up to 128 different colors. Of course, 
a normal program could not effec- 
tively use all of those colors. Too 
many DLIs start slowing down the 
whole program, and sometimes the 
screen layout cannot accommodate all 
of them. In practice, displaying a 
dozen colors is easy, two dozen re- 
quires careful planning, and more 
than that requires a contrived situa- 
tion. 

But DLIs can give more than color. 
They can also be used to extend the 
power of player-missile graphics by 
changing the horizontal position of a 
player. In this way, a player can be 
repositioned partway down the 
screen. A single player can then have 
several incarnations on the screen. If 
you imagine a player as a vertical col- 
umn with images drawn on it, a DLI 
becomes a pair of scissors with which 
you can snip the column and reposi- 
tion sections of it on the screen. Of 
course, no two sections of the player 
can be on the same horizontal line, 
and so two incarnations of the player 
cannot be on the same horizontal 
line. If your display needs allow 
graphics objects that will never be on 



182 December 1981 © BYTE Publications lnc 



Circle 43 on Inquiry card. 



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THE 820 KSR PACKAGE includes 
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CLEARANCE ZENITH COLOR 
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ADM-3A + NEW from Lear Siegler. 
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NEC COLOR MONITOR/RECEIVER 
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DYSAN DISKETTES/Single side, 
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MEMOREX 3401's/51/4"disks $3.25. 
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Call for quantity discounts when 
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MOTOROLA 4116 (200 Nano- 
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NEW SUPER 41-CV SYSTEMS with 

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IMPORTANT ORDERING INFORMATION 

CALL, SCO 343-5504 in Massachusetts. (617) 491-27CO, phones open 
from 8:30 am to 7,CO p.m. Mon-Fri. 1LOO am to 4,00 p.m. Sat 
PO's, Accepted from Dun 8c Bradstieet rated companies— shipment 



contingent upon receipts ot signed purchase order. 
SALE PRICES: Valid for month of magazine date only— all prices sub- 
ject to change without notice. Our Ann Arbor retail store is open 
UOO a.m. to 7CO p.m. Tues-Fri. lOOO am to 5,00 p.m. on Saturdays 



»J^ \y&> WE HAVE IT! 

^ $1895 $5699 



$795 



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COMPLETE SUB-SYSTEM $925. 
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CHOOSE FROM: Silentype Printer 
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FROM MICROSOFT: 16K RAM 
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FROM COMPUTER STATION: 
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OUR APPLE INVENTORY IS COM- 
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At last a CPM based system that looks like it belongs in your office. 
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(1 EACH). 

SPECIAL INTRODUCTORY SYSTEM PRICE SAVE $1000. 
820 SYSTEM I (51/4" DUAL) W/ 820 SYSTEM II (8" DUAL) W/ 

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the same horizontal line, a single 
player can do the job. 

Another way DLIs can be used in 
conjunction with players is to change 
their width or priority. This would 
most often be used along with the 
priority-masking trick described in 
part 3 of this series last month. 

DLIs can also be used to change 
character sets partway down the 
screen. This allows a program to use 
character graphics in a large window 
and regular text in a text window. 
Multiple character-set changes are 
possible. A program might use one 
graphics character set at the top of the 
screen, another graphics character set 
in the middle of the screen, and a 



regular text character set at the bot- 
tom. A "Rosetta Stone" program 
would also be possible, showing dif- 
ferent text fonts on the same screen. 
The vertical reflect bit can be changed 
with a DLI routine, allowing some 
text to be right side up and other text 
to be upside down. 

The proper use of the DLI requires 
careful layout of the screen display. 
Designers must give close consider- 
ation to the vertical architecture of 
their displays. The raster-scan tele- 
vision system is not two-dimension- 
ally symmetric; it has far more ver- 
tical structure than horizontal struc- 
ture. This is because the pace for 
horizontal screen drawing is about 



200 times faster than the pace for ver- 
tical screen drawing. The Atari 
400/800 display system was designed 
specifically for raster-scan television, 
and it mirrors the anisotropy of the 
raster-scan system. The Atari 
400/800 display is not a flat, blank 
sheet of paper on which you draw; it 
is a stack of thin strips, each of which 
can take different parameters. The 
programmer who insists on designing 
an isotropic display wastes many 
opportunities. You will achieve 
optimal results when you organize 
the information you wish to display 
in a strong vertical structure. This 
allows the display-list interrupt to be 
used to its greatest potential. ■ 



IMPORTS 




EPSON MX-80'8/100'8 

Call for prices! 

OkldataM-80 $365 

Okidoto M-82A $499 

Okidata M-83A $765 

HIGHSPEED 




Anodex 9500/9501 ..„ $1245 

Tl 810 Basic $1249 

Doiosouth - 1 80 

New CP-Grophlcs call 



LETTER QUALITY 




Cltoh Starwrirer-IP $1324 

Cltoh Sfarwrirer II S .... $1595 

NEC 3500 $1995 

NEC 7710/7730 $2340 

Diablo 630 

w/rractors $2295 



G-LTnniinE* 



LOW COST 




MORTHSTAR 

Durned and tested - backed by fast warranty 
service. Exclusive Soil® CP/M ■ Increases drive 
capacity. Octals and Winchesters available. 
Our Northstors are better than "factory sealed" 
■ call us- we'll fell you why. (free games disk). 

HRZII64KDD $2795.00 

HRZII64KQuad $3095.00 

Advantage Call 




TELEVIDEO 

A new line of micros-serviced locally by 
General Electric. System I Includes 64K RAM. 
CP/M*."' 1MG on floppy, and diagnostics. 

$2385 

$5349 




ALTOS 

Single user 8000-2 Includes dual o" double 
density drives (1 Mg. capacity), rwo serial 
pons, rwo parallel ports, and CP/M H . 
Coll for other Altos prices. 
ACS-8000-2 w/CP/M® $2849 

ACS-8000-15w/MP/M® ... $4195' 




ZENITH 

The all-in-one compurer rhor's backed by 
your local Zenith/Hearh service center. Green 
Screen, CP/M* and Supercalc Incl. 

Z89 w/48K, 2 SIO's $2144 

Z90w/64K, 2SIO's $2095 



m.3 



Closed Dec. 24th ■ Jan. 3rd 



/ \ 

Scottsdale Systems^ 

6730 E. McDowell Rood, Suite 1 10, Scottsdale, Arizona 85257 

S (602)941-5856 



Call 8-5 Mon.-Fri. 
(We Export) TWX 910-950-0082 (IMEC SCOT) 




ADDS Viewpoint $559 

Televideo910 , $589 

Hozeltine Esprit $589 

SoroclQ 130 $589 

TELEVIDEO 1 




Televideo 912 
Televideo 920 
Televideo 950 



TERMINALS 




Ampex D80 
D80 Amber 
Mime Acr 5A 
ADM - 3A 
Soroc IQ 120 



$925 
$969 
$799 
$775 
$729 



MORE PRINTERS 



Paper Tiger 460G $789 

Paper Tiger 560G $1129 

Cenrronlcs 739P $649 

Centronics 739S $729 

DECLA34AA $1049 



NECPC-B023A $639 

Molibu 

Dual Mode 200 $2395 

Mannesmann-Tally 

MT-1805 $1645 



ORDERING 

MAIL ORDER ONLY • 

2% cosh discount included/charge cards add 2%. Prices subject to change, product 
subject to availability. Arizona residents add 5%. F.O.D. point of shipment Scottsdale. 
0-20% restocking fee for returned merchandise. Warranties included on all products. 
Personal checks take 3 weeks to clear. 
CP/M and MP/M ore registered trademarks of Digital Research. 



THE LAST MEMORY 




64K STATIC RAM/EPROM BOARD 

At last a 64K STATIC memory board for S100 systems. But it's not just a 64K static RAM board, EPROM's can 
also be intermixed with RAM making it the only memory board needed for S100 systems. That's why we call it 
THE LAST MEMORY. 



• 64 K DENSITY 

THE LAST MEMORY uses the new 2016 byte-wide 
16K static RAM to achieve a board density twice that 
possible with old 2114 static memories. 



• 2716 EPROM COMPATIBLE 

A separate board is no longer required for EPROM's 

containing monitors, bootstrap loaders, etc. 

2716 EPROM's can be inserted into the board without 

modification. 



• SIMPLE ADDRESS DECODING 
Where memory is required, just plug a RAM or 
EPROM in the corresponding socket. Empty memory 
sockets occupy no memory space, providing compat- 
ibility with memory mapped I/O devices. 



• EXTENDED ADDRESSING 

THE LAST MEMORY includes the IEEE S100 
extended addresses. These are fully decoded allowing 
expansion to a full 16 megabyte system memory. 

• FAST 

The standard board allows 4 MHz operation. 

• LOW POWER 

Only one memory IC is ever active in byte-wide 
memory systems. The result is far less power con- 
sumption than older 16K static memory boards. 

• LOW COST 

Its best feature is the price: 





Kit 


A&T 


RAM-less Board 


99.99 


139.99 


16K RAM 


249.99 


289.99 


32K RAM 


389.99 


429.99 


48K RAM 


519.99 


559.99 


64KRAM 


639.99 


679.99 



0DH 



Circle 394 on inquiry card. 



static memory systems 

15 So. Van Buren Ave. Suite 209 

Freeport, Illinois 61032 (815) 235-8713 



VISA 



BYTE December 1981 187 



Unbeatable prices 



Orange Micro 



EPSON PRODUCTS 



EED KIT 



range Micro 




HERE AT LAST! A friction 
feed kit for your EPSON 
MX 80/70. The kit allows the 
user to convert his Epson 
printer to a friction feed and 
pin feed mechanism. 

The friction feed will 
accept single sheets of your 
letterhead, or multiple 
copy forms such as invoices 
with up to 4-part carbon copies, 

The pin feed replaces the adjustable sprocket mech- 
anism. It allows use of 9/ 2 " wide continuous fanfold 
paper which is an industry standard size. 

No drilling required. Installation takes about 30 
minutes. All parts are included with easy to follow 
instructions. $75.00 DEALER INQUIRIES INVITED. 



9 x 9 dot matrix • Lower case descenders • 80 CPS 
• Bi-directional, logic seeking • 40, 66, 80,132 columns 
per line • 64 special graphic 
characters ■ TRS-80 Com- 
patible • Form handling • 
Multi-page printing • 
Adjustable tractors 
MX 80 (List $645) S Call 
Graftrax-80 Dot Graphics 
Upgrade (List $95)$ Call 
MX 80 FT includes Friction 
Feed 



$ Call 



EPSON MX 7 




Super low-priced dot res- 
olution graphics -5x7 dot 
matrix ■ User replaceable 
printhead & Top of Form 
MX 70 (List $450)$ Call 



Same basic features as 
the MX 80 • PLUS friction 
feed for single sheets • 
PLUS 15" wide carriage 
MX 100 . (List $995)$ Call 




LETTER QUALITY PRINTERS 



Daisy Wheel Letter 
Quality 25 CPS (Optional 
45 CPS) • Typewriter quality 

• Centronics parallel • RS 
232 Serial (Optional) ■ Pro- 
portional spacing • Bi-direc- 
tional • Programmable VFU 

• Self test • Diablo compatible • 
tractors) • 136 printable columns 
C ITOH STARWRITER 



High Speed Letter Qual- 
ity • 55 CPS • Typewriter 
quality • Bi-directional • 
Plotting & Proportional 
spacing 
77XX RO, Serial/Parallel 

(List $3055) $2575 




Friction feed (Optional 

■ Manufactured by TEC 

(List $1895)$ Call 




QUME 9/45 typewriter quality 
DIABLO 630 typewriter quality 



S Call 
$ Call 




•!• 



rj 



'tifflgV^ Dot graphics • 100 CPS • Bi-direcu 

logic-seeking • Tractors & friction feed • 5-Alphabel font 
• 8 character sizes • Proportional spacing 
NEC 8023 DOT MATRIX (List $795) $ Call 



TELEVIDEO CRT'S 



TVI910, TVI912C, TVI920C, TVI950-Please call toll 
free. Prices are too low to advertise $ Call 





CENTRONICS 739-1 (Paralle 
CENTRONICS 739-3 (Seria 



With graphics and word 
processing Print Quality • 18 
x 9 dot matrix; suitable for 
word processing - Underlin 
ing • proportional spacing 

• right margin justification • 
serif typeface • 80/100 
CPS • 9!4" Pin Feed/Ft 
feed • Reverse Platen 

• 80/132 columns • Top 
of Form 

(List $955) $Call 
(List $1045) $815 






.technical expertise. 



The printer specialists. 



Dot Graphics. Wide Car- 
riage • 11 x9 dot matrix, 
lower case descenders • 
Dot resolution graphics • Bi- 
directional, logic seeking 
■ Upto200CPS • RS232 
Serial & Parallel • Forms 
control • X-ON/X-OFF • Up 
to 6 part copy. 
UMADEX9501 





(List $1650) $1350 



IDS460G 
IDS560G 



Dot Resolution Graphics, 
quality print, speed 9 wire 
staggered printhead with 
ower case descenders • 
Over 150 CPS ■ Bi-direc- 
tional, logic seeking • 8 
character sizes; 80-132 col- 
umns • Adjustable tractors 
• High-resolution dot graph- 
ics • Proportional spacing 
& text justification 

(List $1094)$ Call 
(List $1394)$ Call 



INTERFACE EQUIPMENT 

CCS APPLE SERIAL Interfaces Cable $150 
ORANGE INTERFACE for Apple II parallel 

interface board & cable $110 
TRS-80 CABLES to keyboard or Exp. Interface ... $ Call 

NOVATION D-CAT direct connect modem $ Call 

ATARI, NORTHSTAR printer cables $ Call 

ALL EPSON ACCESSORIES $ Call 



THEGRAPPLER 



TM 



The Grappler™ interface 
card is the first to provide 
on-board firmware for Apple 
high resolution dot graph- 
ics. No longer does the user 
need to load clumsy soft- 
ware routines to dump 
screen graphics — it's all in 
a chip Actually, it's our 
E-PROM, and it is replace- 



able to accommodate the Anadex, Epson MX-70, 80* 
and 100, IDS Paper Tigers, Centronics 739, NEC 8023, 
C ITOH Prowriter. and future graphic printers. The 
Grappler™ accepts 18 software commands including 
Hi-Res inverse, 90° rotation, double size, and much 
lore Invented by, and available from Orange Micro and 
)range Micro dealers only. $ Call for price. 

•Requires GRAFT RAX 80 



VISIT OUR RETAIL STORES 

If you live in California, or are visiting don't miss our 
two Printer Stores. Expert consultation and know-how 
is available to assist you in getting the best printer for 
the application .We provide live demonstrations for a wide 
selection of Printers. 





SHERMAN OAKS, 13604 Ventura Blvd., (213) 501-3486 
ANAHEIM, 3150 E. La Palma, Suitel, (714) 630-3622 
Store Hours: M-F 10-6, Sat. 10-4 

At Orange Micro our printer specialists fit the right 
printer to your application. Call us today for free consul- 
tation (and don't forget to ask for your free catalog). 

Phone orders are WELCOME, same day shipment Free use o( VISA 
and MASTERCARD. COD's accepted Personal checks require 2 weeks 
to clear. Manufacturers warranty Included on all equipment Prices sub- 
ject to revision 

CALL FOR FREE CATALOG 
TOLL FREE (800) 854-8275 

CA, AK, HI (714)630-3322. 



Circle 319 on Inquiry card. 



Orange Micro 



inc. 

31 50 E. La Palma, Suite G, Anaheim, CA 92806 





How to Build a Maze 



David Matuszek 

Department of Computer Science 

8 Ayres Hall 

University of Tennessee 

Knoxville TN 37916 



Mazes are fun to solve. With a little 
imagination, mazes can be incorpor- 
ated into many different computer 
games. If you know how, it's a simple 
matter to use the computer to gener- 
ate random mazes. 

A traditional maze has one starting 
point and one finishing point. In ad- 
dition, all locations inside the maze 
are reachable from the start, and 
there is one and only one path from 
start to finish. While it is easy to place 
doorways and barriers randomly in- 
side a maze, it is more difficult to 
satisfy the two latter constraints. This 
article describes a fairly simple 
method that efficiently produces a 



random traditional maze. 

The General Approach 

We begin with a rectangular array. 
Each cell of the array is initially com- 
pletely "walled in," isolated from its 
neighbors (see figure 1). 

Secondly, we judiciously erase 
walls inside the array until we arrive 
at a structure with the following 
property: for any two cells of the ar- 
ray, there is only one path between 
them. Thus, any cell can be reached 
from any cell, but only by a single 
unique path (see figure 2). Computer- 
science jargon refers to such a struc- 
ture as a spanning tree, and it is the 



creation of this spanning tree that is 
the tricky part of building a maze. 

Finally, the border of the maze is 
broken in two places to provide a 
start and a finish position. Since there 
is a unique path between any two 
cells of the maze, there will be a 
unique path from start to finish. 
Hence, start and finish can be chosen 
in any convenient manner, say, at 
random locations on opposite sides of 
the maze (see figure 3). 

Building the Spanning Tree 

Starting with a fully "walled-up" 
array (see figure 1), pick a single cell 
in the array and call this cell the 



Figure 1: The initial array from which the 
maze will be constructed. 




Figure 2: One possible spanning tree for 
the array in figure 1. 



s 



i_h 



Q 



Figure 3: The spanning tree from figure 2 
with possible entry and exit points added. 



190 December 1981 © BYTE Publications Inc 



Circle 20 on inquiry card. 



Amdek 



From picture perfect:. 

To letter 







pproved 



Amdek 
Video-3i 



At Amdek, we make monitors for people who 
demand state-of-the-art color. And for people who 
know that crisp, clear text display is an art in itself. 

Our versatile Color-1 13" video monitor features 
standard NTSC composite input, front-mounted con- 
trols and a built-in speaker with audio circuit. Our 
popular Video-300 12" Green Phosphor monitor has an 
easy-to-read, non-glare screen, 18 MHZ band width 
and 80 x 24 character display. 

Both offer easy portability, with lightweight 
cabinetry and molded-in handles. And both are fully 



compatible with most computer and word processing 
systems. So compare our performance with other 
monitors. Then compare prices. For quality and value, 
you'll choose Amdek. 

NEW THIS FALL: our advanced high resolution 
Color-II monitor with interface board for Apple II com- 
patibility. Color-II features RGB, TTL input and 560(H) 
x 260(V) resolution for crisp 80 x 24 character display 
and exceptionally sharp color graphics. Ask your 
dealer about an Amdek Color-II, Color-I, or Video-300 
monitor today. 



2420 E. Oakton Street, Suite "E," Arlington Heights, Illinois 60005 (312) 364-1180 TLX: 25-4786 



a b c d e 

Figure 4: Initial steps involved in building a maze. The cell added at each step is marked with an asterisk. The next cell to be added to 
the maze will be selected from the shaded frontier cells. 



spanning tree. Then adds cells one at 
a time to the spanning tree until it 
fills the entire array. 

At any point during this procedure, 
there will be three types of cells in the 
array: 

• those that are already in the span- 
ning tree 

• those that are not in the spanning 
tree, but are immediately adjacent 
(horizontally or vertically) to some 
cell in the spanning tree (we call these 
cells frontier cells) 

• all the other cells 



The algorithm follows: 



1. Choose any cell of the array and 
call it the spanning tree. The four cells 
immediately adjacent to it (fewer if it 
is on an edge or in a corner) thus 
become frontier cells. 

2. Randomly choose a frontier cell 
and connect it to one cell of the cur- 
rent spanning tree by erasing one bar- 
rier. If it is adjacent to more than one 
cell of the spanning tree (and it could 
be adjacent to as many as four!), ran- 
domly choose one of them to connect 




96K CP/M® 

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"Software with Service' 




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Shipping and handling extra. 
California residents add 6% sales tax. 

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it to, and erase the appropriate bar- 
rier. 

3. Check the cells adjacent to the cell 
just added to the spanning tree. Any 
such cells that are not part of the 
spanning tree and have not previous- 
ly been marked as frontier cells must 
now be marked as frontier cells. 

4. If any frontier cells remain, go 
back to step 2. 

5. Choose start and finish cells. 



Figure 4 shows the first few steps in 
building a maze. In each case the ar- 
ray is shown as it would be just 
before execution of step 2 of the 
algorithm. Note that the newly added 
cell (marked by an asterisk) in figure 
4e was adjacent to two cells in the 
spanning tree, yet it was connected to 
only one of these (the one to its left) 
by randomly choosing and erasing 
one barrier. 

If you're mathematically inclined, 
it is easy to show by induction that 
this process results in a>spanning tree. 
When the tree consists of a single cell, 
there is (vacuously) only one path be- 
tween any pair of cells. As each new 
cell is added, it forms no new paths 
between cells already on the tree 
(since the tree is a dead end), and 
there is ; exactly one path from the new 
cell to any other cell (you can get out 
via only one cell, and from that cell 
there is only one path). Finally, the 
process ends when there are no more 
frontier cells (cells adjacent to the 
spanning tree but not in it), and this 
can happen only when all cells have 
been absorbed into the spanning tree. 

Implementation Details 

You should store in each cell of the 



192 December 1981 © BYTE Publications Inc 



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5a 



5b 





5c 



Figure 5: For an m by n maze to be dis- 
played on a computer graphics system, a 
resolution of at least 2m + 1 by 2n + l 
must be available. The 4- by 4-maze array 
of figure 5a requires a graphics array of 9 
by 9. The initial cells of the 4 by 4 array 
are shown displayed using the 9 by 9 
resolution in figure 5b. The finished maze, 
with openings between the cells where 
paths exist, is shown in figure 5c. 



array a number indicating: 1. 
whether it is in the spanning tree, in 
the frontier, or in neither; and 2. if it 
is in the spanning tree, which of the 
cell's barriers have been erased. One 
possibility is to use — 1 for frontier 
cells, positive numbers for cells, 
positive numbers for cells in the span- 
ning tree, and for all other cells, 
any cell of the spanning tree is open 
to at least one other cell, I suggest the 
following encoding: start with O in 
each cell, add 1 if the barrier on the 
right is erased; add 2 if the barrier 
below is erased; add 4 if the barrier 
on the left is erased, and add 8 if the 
barrier above is erased. The result 
will be a number from 1 to 15 that 
specifies exactly which combination 
of barriers has been erased. (Decod- 
ing this number shouldn't be too hard 
if you work with binary numbers.) 
Note that when you erase a barrier 
between two cells you will have to 
add the appropriate numbers to each 
of them. 

The minor exception mentioned 
above is the initial cell of the span- 
ning tree, immediately after step 1 of 
the algorithm (see figure 4a). Since it 
is the first, it is not yet open to any 
other cell. Give it the value 16 (or 
100, or 1984, if you prefer) so that it 
will be positive, and subtract this 
number out again in step 5. 

Now that the array representation 
has been settled, let's discuss efficient 
implementation of the algorithm. In 
step 2 a frontier cell was randomly 
chosen. To prevent bumbling around 
in the array, you must keep a list of 
those cells. This can be simply ac- 
complished by storing the indices of 
the n cells of the frontier (each of 
which is specified by a row number 
and a column number) in the first n 
locations of two arrays, R (row num- 
bers) and C (column numbers). A 
frontier cell can be quickly chosen by 
randomly choosing a k less than or 
equal to n, and using the cell whose 
indices are given by R(/c), C(/c). 

Since the order of the n frontier cell 
locations in arrays R and C is not im- 
portant, the following code suffices to 
remove the chosen cell k: 
R(k) = R(n) 
C(fc) = C(n) 
n = n — 1 



194 December 1981 © BYTE Publications Inc 



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When this frontier cell is added to 
the spanning tree, some of the cells 
adjacent to it (those having a zero 
value) become new frontier cells, 
and their locations must be inserted 
into the R and C arrays. Adjacent 
cells with value — 1 are already fron- 
tier cells and already have their loca- 
tions recorded in the R and C arrays; 
they must not be inserted again. 

Finally, how large should arrays R 
and C be? For an m by n array, 
analysis shows that in the worst case 
(2/3) mn locations will be required, 
but practical experience shows that 
3(m + n) is almost always enough. 
However, if you use the latter figure 
there is a slight probability that the 
program will fail. 

Concluding Remarks 

While we have discussed building a 
maze, nothing has been said regard- 
ing how to display it. That depends 
entirely on your particular hardware 
and software; the answers are dif- 
ferent for the display screen of a 
Commodore PET than for that of an 
Apple II, and different again for a 
character printer. 

To display a maze on a screen with 
graphics capabilities, the following 
scheme is appropriate. For an m by n 
maze, you need to be able to display 
at least 2m + 1 points vertically and 
2n + l points horizontally — the 
"cells" will be those points at the in- 
tersection of even-numbered rows 
with even-numbered columns (see 
figures 5a through 5c). Maze building 
on the screen proceeds exactly as in 
figures 1 through 3, except that the 
walls are necessarily thicker. 

To print a maze out, the same gen- 
eral scheme is used with, say, "X" 
characters for walls and blanks for 
paths (see figure 6). Of course, you 
can't erase an X once it is printed, so 
it will be necessary to build the entire 
maze internally before printing it. 
Then you can decipher and print the 
maze one row at a time. 

As a final note, if you are an afi- 
cionado of hexagonal grids, the maze 
algorithm is easily modified for other 
than rectangular grids. Implementa- 
tion may be a bit messy — but then, 
implementation is always messy. ■ 



196 December 1981 © BYTE PublicaBons Inc 



Circle 447 on Inquiry card. 



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Toward a Structured 6809 
Assembly Language 

Part 2: Implementing a Structured Assembler 



Assembly-language programmers 
can have their cake and eat it too. 
They need not be shut out of the 
world of structured programming in 
order to make the most efficient use 
of a particular computer. Part 1 of 
this article showed a set of structured 
control statements that can be added 
to the 6809 assembly language. Now 
the magician will pull back the cur- 
tain to show how it was all done: I 
will present the actual code for the 
MC6809 structured macros and ex- 
plain their operation. 

However, I will not stop there. As 
several areas of programming-lan- 
guage design and implementation 
come together to produce a struc- 
tured assembly language, it is tempt- 
ing to look beyond the present and 
try to visualize where these tech- 
niques might lead. This article will 
conclude with some speculation on 
just how "high-level" an assembly 
language might become. 

It is not necessary to buy a new 
assembler in order to use these struc- 
tured contol statements. Any as- 
sembler that allows user-defined 
macroinstructions will allow the im- 
plementation of structured control 
statements. Before going into a de- 
tailed presentation of the Motorola 
MC 6809 macroassembler, I would 
like to discuss macros in general for 
those readers who may not be 
familiar with them. 



Listing and figure caption numbers con- 
tinued from Part 1. 



198 December 1981 © BYTE Publications Inc 



Gregory Walker 

Motorola Inc M2880 

3501 Ed Bluestein Blvd 

Austin TX 78721 



What Is a Macro? 

Macros, like subroutines, are a 
way of assigning a single name to a 
complex sequence of operations. 
While subroutines are found in vir- 
tually all programming languages, 
macros are much less widely used. 
Macros and subroutines have many 
similarities and one major difference. 
First we will look at the similarities. 

In assembly language, macros and 
subroutines are similar in appearance 
and in the way they are used. Each 
must be defined before it is used (ie: 
its name must be associated with the 
sequence of instructions that perform 
its operation). Then, whenever that 
sequence of operations is needed in a 
program, the subroutine or macro is 
called. 

With a subroutine, the instructions 
that define its operation exist only 
once, and a "call" instruction trans- 
fers control to that subroutine from 
every place its operation is needed. A 
macro is different in that the instruc- 
tions that define its operation are 
inserted directly into a program 
wherever they are needed. Thus, an 
obvious difference between a subrou- 
tine and a macro is that a subroutine 
reduces program size because its in- 
structions exist in memory only once, 
while a macro takes more memory 
because its instructions are stored 



once for each time the macro is used. 
A macro is also faster because the 
subroutine CALL and RETURN in- 
structions are not needed. 

The above difference is technically 
correct, but it misses the truly signifi- 
cant difference between subroutines 
and macros: a macro is expanded at 
translation time, while a subroutine is 
expanded at execution time. By 
"expanded," I mean the operation of 
replacing a single name with the com- 
plex sequence of instructions that de- 
fines its operation. An example 
should clarify this distinction. 

Suppose I want to be able to shift 
any of the microprocessor's three 
index registers to the right. Using sub- 
routines, I will need three separate 
subroutines, one for each register. 
These subroutines are given in listing 
10. Here each subroutine has an im- 
plicit parameter — the register to be 
shifted right. Having written these 
subroutines, I can now use them by 
inserting a call instruction into tta. 
program by using the form: 



or: 



LBSR SHRTX 
LBSR SHRTY 



At translation time, each subrou- 
tine will be translated from assembly 
instructions into the equivalent 
machine instructions and placed at a 
particular location in memory. 
Similarly, the LBSR SHRTX will be 
translated to the machine instruction 
that branches to the location where 
SHRTX starts in memory. In essence, 

Text continued on page 204 
Circle 234 on inquiry card. > 



THE COMMODORE COMPUTERS 

"FROM s 300 TO $ 1995, THEY COST LESS AND GIVE 
YOU MORE FOR YOUR MONEY. READ OUR CHART." 



—William Shatner 



The idea of a computer in every office and home used to be 
science fiction. Now it's becoming a reality. The question is, 
with so many to choose from, which computer should you 
buy? When you consider the facts, the clear choice is 
Commodore. 

COMPARE OUR $995 COMPUTER 



FEATURES 


COMMODORE 
4016 


APPLE 
II 


IBM 


Base Price 

12" Green Screen 

IEEE Interface 

TOTAL 
Upper & Lower 
Case Letters 
Separate Numeric 
Key Pad 
Intelligent 
Peripherals 
Real Time Clock 
Maximum 5V2" Disk 
Capacity per Drive 


$995 
Standard 
Standard 

$995 

Standard 

Standard 

Standard 
Standard 

500K 


$1,330 
299 
300 

$1,929 

NO 

NO 

NO 
NO 

143K 


$1,565 
345 
NO 


$1,910 

Standard 

Standard 

NO 
NO 

160K 


Prices arc as of the most recent published price lists, September, 1981 and approximate the 
capabilities of the (16K) PET 11 4016. Disk Drives and Printers are not included in prices. Models 
shown vary in their degree of expandability. 



Many experts rate Commodore Computers as the best 
desk-top computers in their class. They provide more storage 
power— up to 1,000,000 characters on 5 Va" dual disks — than 
any systems in their price range. Most come with a built-in 
green display screen. With comparable systems, the screen is 
an added expense. Our systems are more affordable. One 
reason: we make our own microprocessors. Many 
competitors use ours. And the compatibility of peripherals 
and basic programs lets you easily expand your system as 
your requirements grow. Which helps explain why 
Commodore is already the No. 1 desk-top computer in 
Europe with more than a quarter of a million computers sold 
worldwide. 

WE WROTE THE BOOK ON SOFTWARE. 

The Commodore Software Encyclopedia is a com 
prehensive directory of over 500 programs for 
business, education, recreation and personal use. 
Pick up a copy at your local Commodore dealer. 



FULL SERVICE, FULL SUPPORT. 

Commodore dealers throughout the country offer 
you prompt local service. In addition, our new 
national service contract with TRW provides 
nationwide support. Visit your Commodore 
dealer today for a hands-on demonstration. 





I Commodore Computer Systems 
681 Moore Road 
King of Prussia, PA 19406 



Canadian Residents: 

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3370 Pharmacy Avenue 

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Please send me more information. 

Name 





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COMPUTER 



Minicomputer performance in 



Multi-user. Multi Tasking. Decision I™ memory man- 
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Multi-purpose IEEE696/S-100. Decision I utilizes the 
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compatibly with UNIX." Thus, UNIX programs will 
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An unmatched software base. 

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ports all system calls source 



IBM 360 and 370 are trademarks of IBM Corp. 
Wunderbuss is a registered trademark of Morrow Designs 
Decision I and M/OS are trademarks of Morrow Designs 
UNIX is a trademark of Bell Laboratories, Inc. 
CP/M is a trademark of Digital Research Corp. 



ONI 



a multi-user Microcomputer. 




boards, controllers and software allow you to 
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Complete information? See your computer dealer. 

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LOOK TO MORROW 
FOR ANSWERS. 



/ 



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Circle 286 on inquiry card. 



Introducing, for PDP-11 rsx,rsts/e, and RT-11 users 

Kscal-2 



TheTime Machine 



The First Dimension: Performance 

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Pascal-2 programs run as fast as Fortran iv- 
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The Second Dimension: Structure and Portability 

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Our 2,000 customers use Pascal for such 
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The Fourth Dimension: Our Past and Future 

The core of our technical group has been 
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Before releasing our PDP-11 product, we deliv- 
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the UNIX operating system. We're committed 
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Call or write. We'll send benchmark details, a 
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Pascal-2 manual (specify rsx, RT-11, rsts/e). 



PDP, VAX, RSX, RSTS/E, RT-11, and FORTRAN IV-PLUS are trademarks of Digital 
Equipment Corporation. MC68000 is a trademark of Motorola Inc. UNIX is a 
trademark of Bell Laboratories. 



RlSCal-2: The Dimensions of Performance 

Ask for a free 18" x 24" poster of this photograph. 



Network Computer Services 

6 Cunningham Street 
Sydney 2000, Australia 
Telephone: 211-2322 
TLX: 25523 

Valley Software, Inc. 

6400 Roberts Street, #390 
Burnaby, BC Canada V5G 4G2 
Telephone: 604-291-0651 



Hourds Computing, Ltd. 

7-8 Mill Street 

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Telephone: 0785-44221 
TLX: 36540 

Real Time Products 

1 Paul Street 

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Rikei Corporation 

1-26-2 Nishi Shinjuku 
4316 Shinjuku-ku 
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AC Copy 

Kurbrunnenstrasse 30 
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Telephone: 0241-506096 
TLX: 832368 



Periphere Computer 
Systems GmbH 

Pfalzer-Wald-Strasse 36 
D-8000 Munchen 90 
W. Germany 
Telephone: 089/681021 
TLX: 523271 



Oregon 
Software 

2340 S.W. Canyon Road 
Portland, Oregon 97201 
(503) 226-7760 
TWX: 910-464-4779 



Circle 322 on inquiry card. 



Circle 387 on inquiry card. 




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Listing 10: Subroutines for 16-bit right-shift operation. 



* SHIFT X-REGISTER RIGHT ONE BIT. 
* 

SHRTX EXG X, D 

LSRA 

RORB 

EXG D, X 

RTS 
# 

* SHIFT Y-REGISTER RIGHT ONE BIT. 

SHRTY EXG Y, D 

LSRA 

RORS 

EXG D.V 

RTS 
# 
» SHIFT U-REGISTER RIGHT ONE BIT. 

SHRTU EXG U, D 
LSRA 
RORB 

EXG D, U 
RTS 

Listing 11: Assembly-language macro to shift a 16-bit register value one bit to the 
right. 

# 

* Shift a 16-bit register right one bit. 

SHRT MACR 

EXG \0, D 

LSRA 

RORB 

EXG D, \0 

ENDM 



Text continued from page 198: 
there has been no expansion yet, 
because the subroutine call still refers 
to the subroutine by a single name (ie: 
its starting location). 

During execution, the computer 
will step through the program, per- 
forming each instruction in turn. 
When it comes to the machine code 
for LBSR SHRTX, control will trans- 
fer to the beginning of the SHRTX 
subroutine, and the computer will 
perform the instructions that define 
SHRTX. At the end of the subroutine, 
execution will return to the instruc- 
tions following the subroutine call. 

This explanation will seem like old 
hat to anyone who has written a sub- 
routine, but the details are necessary 
in order to show that the subroutine 
has been expanded at execution time. 
Only when the subroutine call is ex- . 
ecuted does the call, in effect, expand 
into the operations that define it. 

With the subroutine case firmly in 
mind, you may have already guessed 
how macros are expanded at transla- 
tion time. Listing 11 shows the shift- 
right operation written as a macro for 
the MC6809. In this case, one macro 
suffices to provide the shift-right op- 
eration for all three registers. 



The \ in listing 11 represents a 
macro parameter that is replaced with 
a register name when the macro is ex- 
panded. The \ refers to the first pa- 
rameter in the macro call line; 
wherever the \ appears in the 
macro, the first parameter will be 
substituted in its place. (The substitu- 
tion is purely a text manipulation. 
The characters that make up the first 
parameter in the macro call are sub- 
stituted for the \ characters in the 
macro body.) A macro call is written 
by simply placing the macro name as 
an assembly operation with the pa- 
rameters in the operand field of the 
same line. Listing 12 shows examples 
of calls to the SHRT macro and the 
actual instructions generated by the 
macro expansion. 

The instructions that define the 
macro are inserted into the program 
wherever there is a macro call. Ad- 
mittedly they take up more memory 
than a single branch-to-subroutine in- 
struction, but that property is far less 
important than the power you gain 
by being able to substitute specific 
values for the macro parameters dur- 
ing translation. In this case, we have 
defined a similar operation on three 



204 December 1981 © BYTE Publications Inc 



T/Makerll: 
it does a number on VisiCalc ! 



VisiCalc is a fine aid for the computation of numerical 
problems. But it does have two major limitations: it is 
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Unlike VisiCalc, T/Maker II is designed to run on most 
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Works with words as well as numbers. Like VisiCalc, 
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T/Maker II is the most advanced aid for the analysis and 
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T/Maker II turns your small business computer into a 
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With T/Maker II you can easily perform an unlimited 
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fect for such things as: 



• Financial Statements 

• Statistics 

• Profitability Reports 

• Revenue and Expense 
Analyses 

• Portfolio Evaluations 



• Price Lists 

• Rate Structures 

• Expense Accounts 

• Cash Flow 
Projections 

• Checking Account 
Reconciliations 



rows and columns, define the relationships and T/Maker II 
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And when any changes have to be made, simply enter 
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Editing capabilities. As a full-screen editor for word 
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to you exclusively and supported completely by Lifeboat 
Associates, world's largest computer software publisher. 
For more information send us the coupon below. 

' Mail coupon to: Lifeboat Associates, 2018 

1651 Third Ave., NY, NY 10028. Or call (212) 860-0300. 

D Please send me more information on 
T/Maker II. 

□ Please send me a free Lifeboat # * 

Catalog featuring over 200 programs, "JGP" 
including integrated accounting /'T % 

and professional practice systems, 
office tools for bookkeepers and secre- 
taries and sophisticated tools for pro- 
grammers. 



Name- 
Title 



Company— 

Streel 

City 

Stale 



_Zip_ 




T/Maker II is a trademark of P. Roizen. 
CP/M is a trademark of Digital Re- 
search, Inc. VisiCalc is a trademark of 



PersonalSof t ware, Inc. UNIXisatrade- 
mark of Bell Laboratories. RT-11 is a 
trademark of Digital Equipment Corp. 



. . . and much, much more. 

Easy to learn and use. You don't have to be a program- 
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As an example of what T/Maker II can do, see the chart below. The operator entered only the data shown in boldface. 

T/Maker II calculated and reported all the other values. 







— Actual — 




Growth 




Total 




— Projected — 






1978 


1979 


1980 


Rate 


Average 


(000's) 


1981 


1982 * 


1985 


Item A 


42.323 


51.891 


65.123 


24.04 


53,112 


159.34 


80,782 


100,206 


191,262 


ItemB 


45.671 


46.128 


49.088 


3.67 


46,962 


140.89 


50,891 


52,761 


58,791 


Total 


87,994 


98,019 


114,211 


13.93 


100,075 


300.22 


131,673 


152,966 


250,053 


% Item 


48.10 


52.94 


57.02 


8.88 


52.69 


158.1 


61.35 


65.51 


76.49 


% Item 


51.90 


47.06 


42.98 


-9.00 


47.31 


141.9 


38.65 


34.49 


23.51 


Total 


100.00 


100.00 


100.00 


— 


100.00 


300.0 


100.00 


100.00 


100.00 
















*Two intervening years not shown. 



LIFEBOAT WORLDWIDE offers you the world's largest library ol software- Contact your nearest dealer or Lifeboat: 



Lileboat Associates 
1651 Thud Ave. 
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Telex. 640693 (LBSOFT NVK) 
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Lifeboat Associates, Ltd. 
PO Box 125 

London WC2H9LU. England 
Tel: 01-836-9028 
Telei: 893709 (LBS0FTG) 



Copyright © 1981, by Lifeboat Associates 



Lifeboat/Ho 

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Circle 220 on inquiry card. 



BYTE December 1981 



205 



Listing 12: Expansion of macroinstructions. 

Cal 1 Expansion 



LDX 


CAT 


LDX 


CAT 


SHRT 


X 


EXG 


X, D 


STX 


CAT 


LSRA 
RDRD 








EXG 


D, X 






STX 


CAT 


LDY 


DOG 


LDY 


DOG 


SHRT 


Y 


EXG 


Y. D 


STY 


DOG 


LSRA 
RORD 








EXG 


D, Y 






STY 


DOG 



Listing 13: Format for Motorola MC6809 macroassembler directives. 

1) Conditional assembly based on character string comparison. 

IFC ^'character str ing>, <c harac ter string> 
(Statements generated if character strings 
are the same, else skip to ENDC. ) 

ENDC 

2) Conditional assembly based on comparison of a numeric expression 

with zero. 

IFEQ -^numeric expression> 

(Statements generated if expression is equal 

to zero* else skip to ENDC. ) 

ENDC 

3) Assign a new value to a label. 
<label> SET <value> 



different registers by writing only one 
macro — one-third as much program- 
ming as was required by the subrou- 
tine approach. 

In addition to parameter substitu- 
tion, many macroassemblers provide 
the ability to perform conditional as- 
sembly (similar to branching around 
instructions with a conditional 
branch instruction, except that condi- 
tional assembly occurs during trans- 
lation of the program). A test is made 
at translation time, and two different 
sequences of instructions are pro- 
duced, depending on the outcome of 
the test. 

Assemblers also use labels to asso- 
ciate a name with a particular value. 
Labels are usually used to assign a 
written name to a particular memory 
location. In a more general sense, 
though, they can also be used as 
translation-time variables for storing 
numeric values. Listing 13 shows the 
capabilities of the Motorola MC6809 
macroassembler used in the struc- 
tured macros. 

Implementation Details 

Listing 14 shows the macro defini- 

206 December 1981 © BYTE Publications Inc 



tions that add structured statements 
to the 6809 assembly language. The 
first seven macros, PUSH, POP, 
BACK1, RELOP, RELTST, RELCC, 
and REGTST, provide primitive op- 
erations that are used by the struc- 
tured macros. 

PUSH, POP, and BACKl imple- 
ment a translation-time stack, which 
is needed if the structures are to be 
nested one inside another. Two paral- 
lel stacks, each ten levels deep, are set 
up using the labels Si through S10 
and Ll through L10. The symbols SI 
through S10 store the locations of 
branch instructions that are generated 
by the structures. For each branch in- 
struction, the corresponding Ll 
through L10 symbol will store a value 
of 1 or 0, 1 indicating a long branch 
and indicating a short branch. 

The label STKTOP contains a 
value from to 10 that indicates 
which pair of S and L labels is at the 
top of the stack. The PUSH macro 
puts a pair of values on the top of the 
stack by incrementing the value of 
STKTOP. It then stores the values to 
be pushed into the labels that 
STKTOP references. 



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selectable from 10 to 16.7 characters/inch. All char- 
acters can be printed double-width under communi- 
cations command. 



Features Plus 

As standard, each model features forms width adjust- 
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Listing 14: Structured macro definitions. 



PAGE 

* STRUCTURED MACROS FOR ASSEMBLY LANGUAGE PROGRAMMING THE MC6B09 

* COPYRIGHT <C> 1980 BY GREGORY WALKER FDR MOTOROLA, INC. 



EXBUG EQU $F000 
STKTOP SET 
ISLONG SET 



DEFAULT 16-BIT ADDRESS 

STACK INITIALLY EMPTY 

BRANCHES DEFAULT TO SHORT OFFSET 



# 

* PUSH — 

» THIS MACRO SIMULATES A 10-LEVEL STACK USING TEN SYMBOLS 

* WHOSE VALUES ARE REDEFINED TO BE THE VALUES ON THE STACK. THE 

* SYMBOL "STKTOP" CONTAINS A NUMBER FROM TO 10 WHICH INDICATES 

* THE SYMBOL (SI TO S10) THAT CONTAINS THE VALUE ON THE TOP OF THE 

* STACK. A VALUE OF ZERO FOR STKTOP INDICATES THAT THE STACK IS 

* EMPTY. 
* 

PUSH MftCR 

STKTOP SET STKTOP+1 
IFEQ STKTOP-1 

51 SET \0 

LI SET ISLONG 
ENDC 
IFEQ STKTOP-2 

52 SET \0 
L2 SET ISLONG 

ENDC 

IFEQ STKTOP-3 

53 SET \0 

L3 SET ISLONG 
ENDC 
IFEQ STKTOP-4 

54 SET \0 

L4 SET ISLONG 
ENDC 
IFEQ STKTOP-5 

55 SET \0 

L5 SET ISLONG 
ENDC 
IFEQ STKTOP-6 

56 SET \0 

L6 SET ISLONG 
ENDC 
IFEQ STKTOP-7 

57 SET NO 

L7 SET ISLONG 
ENDC 
IFEQ STKTOP-S 

58 SET \0 

L8 SET ISLONG 
ENDC 
IFEQ STKTOP-9 

59 SET \0 

L9 SET ISLONG 

ENDC 

IFEQ STKTOP-10 
S10 SET \0 
L10 SET ISLONG 

ENDC 

IFGT STKTOP-10 

FAIL •»* SYMBOL STACK OVERFLOW ** 

ENDC 

ENDM 

# 

* POP — 

* THE POP MACRO REMOVES THE TOPMOST ELEMENT FROM THE 

* SIMULATED STACK. 



POP MACR 

IFLE STKTOP 

FAIL ** SYMBOL STACK UNDERFLOW »* 

ENDC 

IFGT STKTOP 
STKTOP SET STKTOP-1 

ENDC 

ENDM 



IF STACK IS EMPTY, THEN ERROR 



IF STACK NOT EMPTY, DECREASE 
STACK POINTER BY ONE. 



# 

* BACK1 — — 

* THIS MACRO SETS THE ASSEMBLER'S LOCATION COUNTER TO 



Listing 14 continued on page 210 



The BACKl macro resolves for- 
ward references within a matched 
pair of structured macros. It uses the 
value on the top of the stack as the 
address of an unresolved branch in- 
struction. The L value from the stack 
is given to the symbol ISLONG to in- 
dicate whether the branch to be gen- 
erated is long or short. In addition, 
the ORG (origin) statement causes the 
branch offset to be generated at the 
proper location. BACKl does not 
change the stack. 

The three macros RELOP, RELTST, 
and RELCC process the relational op- 
erators for the IF, IFTST, and IFCC 
macros, respectively. The RELOP 
macro is also used by the WHILE and 
UNTIL macros. RELOP, RELTST, 
and RELCC operate similarly: they 
generate a conditional branch instruc- 
tion that corresponds to the parti- 
cular relational operator used in the 
macro. If the branch is a backward 
reference, the branch is made to the 
value on the top of the stack. If the 
branch is a forward reference, a 
dummy branch is generated. The 
location and size (long or short) of 
this dummy branch instruction are 
pushed onto the stack for later resolu- 
tion. 

The REGTST macro is used by all 
of the structures to test for valid 
MC6809 registers. As with the other 
macros, if an error is detected, an 
error message is printed out using the 
FAIL directive. 

Given the above primitive opera- 
tions, the structured macros them- 
selves can be written by examining 
the equivalent machine code that 
each macro must generate. These 
structured macros are general in 
form and should move easily to as- 
semblers for other computers. The 
primitive operations will have to be 
redefined, depending on the macro 
facilities available on a particular as- 
sembler, and the calculation of 
branch offsets must be changed to the 
use of absolute addresses if the target 
computer does not provide relative 
branch instructions. 

In summary, only three capabilities 
such as the following are needed in an 
assembler to allow the creation of a 
set of structured macros: 

Text continued on page 224 



208 December 1981 © BYTE Publications Inc 



dBASE II 

Written in assembly language (no host language 

required) dBASE can handle up to 65,000 

records ol 32 fields and 1000 bytes each Reads 

existing ASCII tiles Can be run interactively or 

can beprogrammed to produce reports 

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WORDSTAR - 

New version 3 features horizontal scrolling and 

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SPELLSTAR" 

New option for WordStar. Compares words in 
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dictionary. Then returns to WordStar tor 
correction of errors Expandable dictionary. 
Requires WordStar Version 3.0 {If you have 
another version, call for details on updates.) 
List Price $250 00 
Microhouse Price: $1 65.00 

SPELLSTAR • for APPLE 

List Price: $170 00 

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MAILMERGE" 

Option for WordStar. (Requires current version of 

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WORDSTAR TRAINING MANUAL 

Provides sixteen sequential lessons on the 
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SUPERSORT " for APPLE 

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APPLESOFT" COMPILER 

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Bidirectional logic-seeking dot matrix printer. 100 
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C ITOH STARWRITER I 

Serial Version 

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Microhouse Price: $1502.00 



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Letter-quality printer uses plastic and metal 
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Optional tractor: $225. 
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MORROW DISCUS 2D 

8 inch single-sided double-density floppy disk 
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MORROW HARD DISK SUBSYSTEM 
10 Megabyte. Includes S-100 controller card. 
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SCITRONICS REALTIME CLOCK 

For Apple II. Crystal controlled (.002% accuracy) 
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NOVATION AUTO CAT MODEM 

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MICROSOFT APPLE SOFTCARD 

Regular Microhouse price $305.00 Save when 

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Microhouse Price: $290.00 



Software & Manual/Manual Only 

PRICES AND SPECIFICATIONS SUBJECT TO 

CHANGE WITHOUT NOTICE 

CP/M is a registered trademark of Digital Research 

APPLE are registered trademarks of Apple Computers 

Inc. 

WORDSTAR, DATASTAR, MAILMERGE, 

SPELLSTAR. and SUPERSORT are registered 

trademarks of MicroPro International. 

SHIPPING: Add $5 per manual or software package. 
Add $2.50 for COD orders. Call for shipping charges 
on other items. Pennsylvania residents add 6 per cent 
sales tax. 





P.O. Box 498 
Bethlehem, PA 18016 
(215)868-8219 



Software: 

A GOOD/! 



MicroPro's Electronic 
Worksheet $225 



Hardware. 

ITS NEW! 



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Circle 257 on inquiry card. 



Big sale 
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16K... $149.95 
32K... $199.95 
48K... $249.95 
64K... $299.95 




New JAWS-IB 

The Ultrabyte Memory Board 

Due to the tremendous success of our JAWS I, we 
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JAWS-IB in 16K blocks up to 64K. $59.95 
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Total enclosed: $ 

D Personal Check O Money Order or Cashier's Check 

□ VISA □ Master Card (Bank No. ) 



_ Exp. Date . 



Signature 
Print 
Name 



Address _ 

City 

Stale 



.Zip. 



I5t 



NETRONICS R&D Ltd. 

333 Litchfield Road, New Milford, CT 06776 



Listing 14 continued: 

* THE VALUE ON THE TOP OF THE STACK. A FORWARD REFERENCE IS 

* RESOLVED BY FILLING IN THE BRANCH OFFSET AT THE STACKED 

* LOCATION. THE SYMBOL "BACKLNG" IS SET TO INDICATE WHETHER A 

* LONG OR SHORT OFFSET IS TO BE GENERATED. 

* THE CONTENTS OF THE STACK ARE NOT CHANGED BY THIS 

* MACRO. 
* 

BACK1 MACR 

IFEG STKTOP-1 

ORG SI 
BCKLNG SET LI 

ENDC 

IFEQ STKTOP-2 

ORG S2 
BCKLNG SET L2 

ENDC 

IFEQ STKTOP-3 

ORG S3 
BCKLNG SET L3 

ENDC 

IFEG STKTOP-4 

ORG S4 
BCKLNG SET L4 

ENDC 

IFEQ STKTOP-5 

ORG S5 
BCKLNG SET L5 

ENDC 

IFEQ STKTOP-6 

ORG S6 
BCKLNG SET L6 

ENDC 

IFEQ STKTOP-7 

ORG S7 
BCKLNG SET L7 

ENDC 

IFEQ STKTOP-B 

ORG SB 
BCKLNG SET L8 

ENDC 

IFEQ STKTOP-9 

ORG S9 
BCKLNG SET L9 

ENDC 

IFEQ STKTOP-IO 

ORG SIO 
BCKLNG SET S10 

ENDC 

IFLE STKTOP 

FAIL »» REFERENCE WAS MADE TO EMPTY SYMBOL STACK #* 

ENDC 

IFGT STKTOP-7 

FAIL ** STACK TOP POINTER EXCEEDS STACK »* 

ENDC 

ENDM 

# 

* RELOP — 

» THIS MACRO CREATES A RELATIVE BRANCH INSTRUCTION 

* FOR THE 'IF', 'WHILE', AND 'UNTIL' MACROS BASED ON THE 

* RELATIONAL OPERATOR PASSED TO IT AS ITS FIRST ARGUMENT. 

* THE SYMBOL "ISLONG" DETERMINES WHETHER A LONG OR SHORT BRANCH 
» IS GENERATED. A SHORT BRANCH IS GENERATED IF "ISLONG" EQUALS 

* ZERO, ELSE A LONG BRANCH IS GENERATED. 
# 

RELOP MACR 
IFC \0, EQ 

IFEQ ISLONG 

BNE * 

ENDC 

IFEQ ISLONG-1 

LBNE EXBUG 

ENDC 
ENDC 
IFC NO. NE 

IFEQ ISLONG 

BEQ » 

ENDC 

IFEQ ISLONG-1 
LBEQ EXBUG 
ENDC 
ENDC 

IFC \0, LE 
IFEQ ISLONG 
BGT * 
ENDC 

IFEQ ISLONG-1 
LBGT EXBUG 
ENDC 



Listing 14 continued on page 212 



210 December 1981 © BYTE Publications Inc 



Please call 
(213)7060333. 

Our Epson prices 
are so low, 

we're not allowed 
to print them. 



EPSON MX-80 $CALL 

80 cps/9x9 matrix/Lower case with 
true descenders/Bi-directional & 
Logic seeking/Adjustable tractor/ 
Expanded printing/Block graphics/ 
Forms control/Compressed printing/ 
Double-strike printing/Correspon- 
dence quality/Emphasized printing 
mode/Standard parallel interface 

EPSON MX-80 F/T $CALL 

Same features as the MX-80 plus Fric- 
tion Feed. Adjustable removable trac- 
tor is standard for ease of handling 
forms and single sheets. 

EPSON MX -100 F/T $CALL 

Same features as the MX-80 & MX-80 
FA but on 1 5 1 /2 inch carriage for print- 
ing 132 columns with standard 10 cpi 
font or 232 columns in the com- 
pressed character font. The MX-100 is 
complete with Dot Resolution 
Graphics 

Circle 15 on inquiry card. 



EPSON INTERFACES & OPTIONS 

TRS-80MODELI.III CABLE $ 30 SERIAL INTERFACE (2K BUFFER) S 149 

TRS-80 MODEL I Keyboard Interface . . . .$ 95 SERIAL CABLE Male to Male $ 30 

TRS-80 MODEL II CABLE $ 30 DOT RESOLUTION GRAPHICS $ 90 

APPLE INTERFACE & CABLE $ 100 REPLACEMENT RIBBON $ 13 

IEEE 488 INTERFACE $ 60 REPLACEMENT PRINT HEAD (Quiet lype) $ 40 

SERIAL INTERFACE $ 70 EPSON SERVICE MANUAL $ 40 



We built a reputation on our 
prices and your satisfaction. 

We guarantee everything we sell for 30 days. If anything 
is wrong, just return the item and we'll make it tight. 
And, of course, we'll pay the shipping charges. 

We accept Visa and Master Card on all orders. COD 
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Please add S2.00 lor standard UPS shipping and 
handling on orders under 50 pounds, delivered in the 
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orders please add 15% for shipping. California res- 
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31245 LA BAYA DRIVE, WESTLAKE VILLAGE, CALIFORNIA 91362 




BYTE December 1981 



211 



Now with added words! # 

ELECTRIC MOUTH 




From $99.95 kit 



for SI 00, Elf II, Apple 

TRS-80, Level II* 
Now — teach your computer to talk, 
increasing interaction between you 
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That's riRhl: ihe ELECTRIC MOUTH actually lets your computer talk! Installed 
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• Supplied with 1-13 letters/words/phonemes/numbcrs. capable of producing 
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Principle of Operation: The ELECTRIC MOUTH stores the digital equivalents 
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pons (user selectable) are used. 

SPOKEN MATERIAL INCLUDED (Vox I) 



one 


eighteen 


at ' 










two 


nineteen 


cancel 


down is 


of 


second d u 


three 


twenty 


case 




equal it 


off 


set e v 


four 


thirty 


cent 




error kilo 


on 


space f w 


five 


forty 


400hertz lone 


Teel left 




speed g x 


BIX 


fifty 


BOhertz tone 


flow less 




seven 


sixty 


20ms silence 


fuel lesser 


parenthesis start [ z 


eight 


seventy 


40ms silence 


gallon limit 


percent 


stop j 
than k 


nine 


eighty 


BOmi 


silence 


go low 


please 


ten 


ninety 


180ms silence 






the 1 


eleven 


hundred 


320ms silence 


great mark 


point 


time m 




thou so ml 


centi 




greater meter 


pound 


try n 


thirteen 


million 


chec! 








fourteen 


zero 






high mill] 


rate 


volt p 


fifteen 


again 


control 


higher minus 


re 




sixteen 


ampere 
and 


danger 


hour minute 


ready 


a r 


seventeen 


degree 


in near 


right 


b s 


ADDITIONAL VOCABULARY NOW AVAILABLE (VOX IN 


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light 


put 


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fire 




quarter 


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system 


alarm 


correc 




door 


longer 


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'.emperalure 




crease 




fourth 


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"de" 




forwan 


move 






ask 


deposi 




from 


next 


reverse 




assistance 


dial 






no 


red 




attention 


door 




get 


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blue 
brake 
button 


east 




going 


north 


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emergency 


green 
hale 


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replace 




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called 


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safe 




entry 
"er" 




help 


operator 




warning 


caution 


■w 




hurts 






water 


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evacuate 


hold 




send 


wesl 


change 


fail 




hot 




service 


wind 


circuit 


failure 




incorrect pressure 


slow 




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Continental U.S.A. Credit Card Buyers Outside Connecticut i 

TO ORDER 
Call Toll Free: 800-243-7428 

' To Order From Connecticut, or For Technical ! 
J Assistance, call (203) 354-9375 

NETRONICS R&D LTD. 

333 Litchfield Road, New MIlford.CT 06776 , 
Depr BI2 ! 



IISN 



; Please send the items checked below: 

■ „ 

■ □ SlOO'Electric Mouth" kit w/VoxI $ 99.95 i 

J □ Ell II "Electric Mouth" kit w/Vox I S 99.95 ] 

■ □ Apple "Electric Mouth" kit w/Vox I S119.95 I 

« D TRS-80 Level II "Electric Mouth" kit w/Vox 1 $119.95 ! 

I D VOX II (Second Word Set) S 39.95 ! 

' Add S20.00 tor wired tested units Instead of kits. VOXIlpostagea insurant | 

■ SI 00. .ill olhi-rs $300 postans and Insurance. Cdnn. res. .idd snips MX. I 

I Total Enclosed $ ' 

■ I 
*D Personal Check D Cashier's Check/Money Order ! 

• D Visa □ Master Charge (Bank No. ) j 

JAcct.No. Exp. Date | 



• Signature 
I Print 
; Name 



! Address 



;Clty_ 
■ Stale 



.Hp_ 



Listing 14 continued: 



ENDC 

IFC \0, LT 

IFEQ ISLONG 
BGE « 
ENDC 

IFEQ ISLONG-1 
LBGE EXBUG 
ENDC 
ENDC 

IFC \0, GE 
IFEQ ISLONG 
BLT * 
ENDC 

IFEQ ISLONG-1 
LBLT EXBUG 
ENDC 
ENDC 

IFC \0. GT 
IFEQ ISLONG 
BLE * 
ENDC 

IFEQ ISLONG-1 
LBLE EXBUG 
ENDC 
ENDC 

IFNC \0, EQ 
IFNC \0, NE 
IFNC \0, LT 
IFNC \0, LE 
IFNC \0, GE 
IFNC \0, GT 

FAIL ** INVALID RELATIONAL OPERATOR — \0 «* 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDM 

* RELTST — 

* THE 'RELTST' MACRO TESTS THE VALIDITY OF THE 

* RELATIONAL OPERATOR USED WITH AN 'IFTST' MACRO AND 

* GENERATES THE PROPER RELATIVE BRANCH INSTRUCTION 



RELTST MACR 


IFC \0, EQ 


IFEQ ISLONG 


BNE * 


ENDC 


IFEQ ISLONG-1 


LBNE EXBUG 


ENDC 


ENDC 


IFC \0, NE 


IFEQ ISLONG 


BEQ * 


ENDC 


IFEQ ISLONG-1 


LBEQ EXBUG 


ENDC 


ENDC 


IFC \0, GE 


IFEQ ISLONG 


BLT * 


ENDC 


IFEQ ISLONG-1 


LBLT EXBUG 


ENDC 


ENDC 


IFC \0, LT 


IFEQ ISLONG 


BGE * 


ENDC 


IFEQ ISLONG-1 


LBGE EXBUG 


ENDC 


ENDC 


IFNC \0, EQ 


IFNC \0,NE 


IFNC \0, GE 


IFNC \0, LT 


FAIL *» \0 IS AN INVALID RELATIONAL OPERATOR FOR 


ENDC 


ENDC 


ENDC 


ENDC 


ENDM 



'IFTST' #« 



Listing 14 continued on page 214 



212 December 1981 © BYTE Publications Inc 



Circle 264 on inquiry card. 




m 

CPM 

WINCHESTER 
HARD DISK 



4 Mhz 
OPERATION 



• 90 DAY WARRANTY 

• LOCAL DEALER SERVICE 

• MODEL HI COMPATIBILITY 



• CPM OPTION 

• GREATER DISK STORAGE 

• 4 Mhz OPTION 



MOD Hi PLUS/140 

We have taken the basic 16K 
Model 111 expanded the memory 
to 4BK and added our MTI Double 
Density, Dual Disk Drive System. 
System Is fully compatible with 
Radio Shack DOS and peripherals. 



MOD Ml/240 

Same as the MOD ill PLUS/140 

but has double storage capacity, 

and 2 dual headed 40 track 

drives. 



MOD 111/280 

Has 1.5 megabytes of storage 
and utilizes 2 dual headed 80 
track double density disk drives 
with DOS plus 3.3. 



$1998. 



$2449. 
CPM/80 x 24 Display $699. 



$2799. 



MOD MI/WINCHESTER 

Our largest business computer 
system. 5.7 megabytes of 
storage. Includes a 5 megabyte 
Winchester hard disk drive and 
80 track dual head disk drive 
used as back up and for con- 
ventional floppy disk operation. 
$5399. 



4 Mhz Speed-up enhancement $149. 



MTI AUTHORIZED SALES AND SERVICE CENTERS 



Phoenix, AZ (602) 244-9739 

Sierra Vista, AZ . . . (602) 458-2479 
Tempe, AZ, ...... (802) 839-0546 

Tucson, AZ . . (602) 323-9391 

Anaheim, CA . (714) 773-0240 

Covfna, CA (213) 332-4088 

GoletB, CA . (805) 987-7628 

Huntington Beh., CA (714) 842-1345 



Ingle wood, CA . 
Lancaster, CA . 



Ha 



(213) 673-3295 
(80S) 942-S747 



Northridge. CA. . . . (213) 886-9200 
Port Hueneme, CA . (80S) 985-2329 
Redondo Bch., CA . (213) 370-5556 
San Diego, CA. . . .(714) 276-4243 

San Jose, CA (408) 946-1265 

Santa Cruz, CA . . . (408) 427-0836 

Vallejo, CA (707) 694-7550 

Walnut, CA (714) 594-8311 

Groton, CT (203) 445-5166 

Hollywood, Ft ... . (305) 981-1011 



Norcross, GA (404) 449-8982 

Blackfoot, ID (208) 785-1497 

Collins ville. IL . . . . (618) 345-5068 
Shreveport, LA . . . (318) 865-7583 

Anoka, MN (612) 427-5783 

Joplin, MO. ..... . (417) 781-1748 

Missoula, MT (406) 548-8715 

Raleigh, NC (919) 755-1 1 75 

Grand Fords, ND . . (701) 772-7848 
Jericho, NY (516) 997-8668 



Manhasset, NY . . . (516) 869-8335 

Troy, NY (618) 273-8411 

Maumee, OH .... . (419) 893-4288 

Dallas, TX (214) 247-6679 

Cheyenne, WY. . . . (307) 632-9132 

Mexicali, BC (714) 357-4717 

OVERSEAS 

Australia 3877-6946 

Belgium 1663-2452 

Rep. of South Africa .. 2145-1047 



MICROCOMPUTER TECHNOLOGY INC. 

3304 W. MACARTHUR, SANTA ANA, CA 92704 
(714) 979-9923 »1EI.EX 6780401 TABIRIN 



Call or write for free brochure: 

U.S. PRICES, F.O.B. SANTA ANA 

CALIFORNIA AND MAY VARY BY AREA. 



Circle 148 on inquiry card. 



CHOOSE... 

Choose an Apple Desk 




A compact Bi-Level desk ideal for the Apple com- 
puter system. This 42" x 29Vb" desk comes with a 
shelf to hold two Apple disk drives. The top shelf for 
your TV or monitor and manuals can also have an 
optional paper slot to accomodate a printer. It is 
shown here with the optional Corvis shelf which will 
hold one Corvis disk drive. The Corvis shelf is avail- 
able on the 52" x 29'/2" version of the Apple desk. 

Choose a Micro Desk 



^W 



The Universal Micro desk accommodates the S-100 
type microcomputers. The desk is available in four 
sizes: 17.75 inch, 19.06 inch, and 20.75 inch wide 
openings with 24 inch front-to-rear mounting space. 
The fourth size is a 20.75 inch wide opening with a 
26.50 inch front-to-rear mounting space. 

Choose a Mini Rack 



wk 



Mini racks and mini micro racks have standard vent- 
ing, cable cut outs and adjustable RETMA rails. 
Choose a stand alone bay or a 48", 60", or 72" desk 
model in a variety of colors and wood tones. A 
custom rack is available for the Cromemco. 

Choose a Printer Stand 




The Universal printer stand fits the: 

Centronics 700's 
Dec LA 34 
NEC Spinwriter 
Lear Siegler 300' s 



Diablo 1600's & 2300's 
T.I. 810 & 820 
Okidata Slimline 
Anadex 9500's 



Delivery in days on over 200 styles and colors in 
stock. Dealer inquiries invited. 

ELECTRONIC 5<dSTEM5 
FURNITURE 

COMRflNy 

17129 S. Kingsview Avenue 
Carson, California 90746 
Telephone: (213)538-9601 



Listing 14 continued: 



# 

* RELCC — 

» THE 'RELCC MACRO TESTS THE VALIDITY OF THE RELATIONAL 

* OPERATOR FOR AN 'IFCC MACRO AND GENERATES THE PROPER RELATIVE 

* BRANCH INSTRUCTION. 
# 

RELCC MACR 
RELERR SET 
IFC \0, EQ 

IFEQ ISLONG 

BNE # 

ENDC 

IFEQ ISLONG-1 

LBNE EXBUG 

ENDC 
ENDC 
IFC \0, NE 

IFEQ ISLONG 

BEQ * 

ENDC 

IFEQ ISLONG-1 

LBEQ EXBUG 

ENDC 
ENDC 
IFC \0, LE 

IFEQ ISLONG 

BGT * 

ENDC 

IFEQ ISLONG-1 

LBGT EXBUG 

ENDC 
ENDC 
IFC \0, LT 

IFEQ ISLONG 

BGE * 

ENDC 

IFEQ ISLONG-1 

LBGE EXBUG 

ENDC 
ENDC 
IFC \0, GE 

IFEQ ISLONG 

BLT * 

ENDC 



ISLONG- 
EXBUG 



IFEQ 

LBLT 

ENDC 
ENDC 
IFC \0, GT 

IFEQ ISLONG 

BLE # 

ENDC 



ISLONG- 
EXBUG 



IFEQ 

LBLE 

ENDC 
ENDC 
IFC \0, CC 

IFEQ ISLONG 

BCS * 

ENDC 

IFEQ ISLONG- 

LBCS EXBUG 

ENDC 
ENDC 
IFC \0, CS 

IFEQ ISLONG 

BCC # 

ENDC 



ISLONG-1 
EXBUG 



IFEQ 

LBCC 

ENDC 
ENDC 
IFC \0, VC 

IFEQ ISLONG 

BVS * 

ENDC 

IFEQ ISLONG-1 

LBVS EXBUG 

ENDC 
ENDC 
IFC \0, VS 

IFEQ ISLONG 

BVC » 

ENDC 

ISLONG-1 
EXBUG 



IFEQ 

LBVC 

ENDC 
ENDC 
IFNC \0, 



EQ 



Listing 14 continued on page 218 



214 December 1981 © BYTE Publications Inc 



Circle 182 on inquiry card. 



Right for the time. Finally 
someone invented an RS-232C 
compatible calendar/clock system, 
complete with 6-digit display . . . 
and selling for only $249. Hayes 
did it! 

Introducing the Hayes Stack 
Chronograph, the newest addition 
to the Hayes Stack microcomputer 
component series. It allows your 
computer to accurately record all 
of your system activities by date 
and time . . . down to the second. 
Thanks to a battery back-up sys- 
tem, you never have to reset the 
time when your computer is off, 
and it will keep on ticking even when 
there's a power failure. A write- 
protect switch prevents accidental 




Microcomputer Component Systems 

changing of day, date or time. 

Right for the job. The Hayes 
Stack Chronograph is ideal for any 
home or business application re- 
quiring accurate timekeeping. Use 
it for timing everything from lights, 
burglar alarms, or sprinkler systems 
... to sending mail electronically 
(with the Hayes Stack auto-dial 
Smartmodem and your computer) 
. . . logging and recording reports 
or time-sharing access time . . . 



and batching all your messages 
to send at night, when rates are 
lowest. Chronograph helps do 
it all. 

And Chronograph stacks 
up. Keep your computer system 
up-to-date with the Hayes stack- 
ables, including the RS-232C com- 
patible Smartmodem, the most 
sophisticated 300-baud originate/ 
answer modem you can buy. And 
yet, it's probably the easiest to 
use too. 

The Hayes Stack Chronograph 
and Smartmodem are available 
wherever fi ne com puter products are 
sold. It's - 
time. And 
it's now. 



The Hayes Stack Chronograph. 
There's no better time. 




Hayes Microcomputer Products, Inc. 5835 Peachtree Corners East, Norcross, Georgia 30092 404/449-8791 

Hayes Stack is a trademark of Hayes Microcomputer Producls. Inc. © Hayes Microcomputer Products, Inc. 




When You Have To Face A Deadline . . . 




Ince Its Introduction, Paacal/MT + * has been used to produce thousands of 
professional solutions to Industrial, business and systems level application 
problems. In addition to Implementing the complete ISO STANDARD, 
Pascal/MT + ' S contains a host of powerful features and facilities which make 
program construction a snapl 
Pascal/MT + • Is a total programming system including our native machine code com- 
piler, linker, Pascal-level debugger, disassembler, run-time subroutine library and the ex- 
clusive SpeedProgrammlng'" 1 Package. 

With the advent of 16-bit machines and Increasing customers demands, you can no 
longer afford to write programs in anything but a professionally constructed and profes- 
sionally supported package like PascallMT + " . MT MicroSYSTEMS has demonstrated its 
commitment to keeping your programs and programmers productive with our recent in- 
troduction of Pascal/MT + 86 and Pasoal/MT + 68K lor the 8086 and 68000. While 
Pascal/MT + ■ provides the capability to write non-portable programs when the need arises, 
true portability between radically different machines is a reality while still translating 



Into efficient, optimized native machine code. 

Our Pascal/MT + ' compilers and SpeedProgrammlng Package are available on a wide 
variety of processors and operating systems, with more to come! We are continually work- 
ing to provide Innovative solutions to the ever present problem of translating your ideas into 
software solutions. 
The Pascal/MT + ° System 
Compiler: 

Generates ROMable Native Code • Complete ISO Standard (superset of Jensen & Wirth). 
Powerful Extensions Include: 

Modular Compilation, Direct production of binary relocatable modules • Dynamic strings 
• Chaining • Powerful Overlay system • Address and Size returning functions • Bit manipu- 
lation (test, set, clear, shifts) • Byte manipulation (high, low, swap) • Imbedded assembly 
language • Easy linkage to external assembly language • Full NEW and DISPOSE pro- 
cedures • Direct access to I/O ports • Fast floating point, both software and AMD 9511 • 
Accurate 18 digit BCD (fixed point, 14,4) • Include files • Hex literal numbers • and more. , . 



. . . Arm Yourself With Pascal/MT+ 



® 



300000 




Linker: 

Combines relocatable modules Into executable tiles • Can generate Hex format for use 
with PROM programming. 
Interactive Symbolic Debugger: 

Variable display • High-level breakpoints by procedure/function name • Tracing/single 
step by Pascal statement • Procedure/function entry and exit trace available. 
Disassembler: 

Combines a relocatable module with its listing file to produce interleaved Pascal and ap- 
proximate assembly language code. 
The SpeedProgrammlng Package"": 

The SpeedProgrammlng Package is an integrated set of tools which allows you to create 
Pascal/MT+' programs, check them for correct syntax and undefined identifiers, format 
them to display flow of control, and do this all within the editing environment before you 
ever invoke the compiler. Programmers like SpeedProgrammlng because it frees them from 
the time consuming chore of repeated compilations to correct simple syntactic and typing 
errors. Managers find that SpeedProgrammlng improves productivity, thereby reducing 
development costs. SpeedProgrammlng combined with our field tested Pascal/MT+ ' 
package gives you a comfortable, powerful, Interactive programming environment in which 
to create your professional quality software. Your products demand production quality 
tools. Order Pascal/MT+ * with SpeedProgrammlng today! 
Screen Editor: 

User configurable • Standard random cursor movement, file access, search and replace, 
insert, delete, exchange, etc. • Structured language editing features such as automatic in- 
dent, line adjustment, reading from and writing to a file, block text Insertion and duplication. 
• Requires: 24 x 80 CRT (or larger), ASCII Keyboard (7 bit data), random cursor addressing. 
Interactive Syntax Scanner: 

Finds syntax errors In text being edited • Enters SPEED, puts cursor at error, prints error 
text. 
Variable Checker: 

Catches undefined and mis-spelled variables before the compiler is Invoked. 



On-line Reformatted 

Beautify programs in seconds • Clearly shows structure and program flow. 
Source Code Management Tools: 

Automatic Modification Log and Backup utility program. 

PRICING: 'Read carefully, some systems do not include the SpeedProgrammlng Package 
but do Include the compiler, linker, disassembler, debugger and other utilities. 



AVAILABLE NOWI 

•808078085/ZBO without SpeedProgrammlng Price $360.00 

66K or larger CP/M-80 or Heath/Zenith HDOS 
808078085/Z80 complete Including SpeedProgrammlng Price $475.00 

56K or larger CP/M-80 (not available for HDOS) 
8080/8085/Z80 for special MP/M environments Contact Factory 

•8086/8088 without SpeedProgrammlng Price$600.00 

CP/M-86 or MP/M-86, requires 116K program area 

808678088 complete Including SpeedProgrammlng Price $800.00 

•8086/8088 without SpeedProgrammlng for RMX-86 Price $1500.00 

All 8086/8088 packages include 9511 and 8087 support and 
program to convert MT object files into Intel .OBJ 8086 files. 



COMING SOON: 

68000 Cross Compiler System Price (to be announced) 

68000 Resident System with and without SpeedProgrammlng .... Price (to be announced) 



Available on 8" (3740) Single Density Disks. Contact Distributors For Other Formats. 

CPM/, MP/M are trademarks of Digital Research, Inc. 

Heath, Zenith and HDOS are trademarks of Zenith Data Systems. 



FOR: 8080/8085/Z80/8086/68000 



Payment Terms: 

Cash, Check, UPS, C.O.D. 
Mastercard, VISA, 



/ MT Micro SYSTEMS \ 

1562 Kings Cross Drive 
Cardiff, California 92007 (714) 755-1366* 

'We re moving io bigger quarters Call ibis number and 
you'll be (old our new telephone number 



Pricing: 

8080/Z80 - $475.00 
Others Call 



Circle 293 on Inquiry card. 



Circle 90 on Inquiry card. 




Make Your Dreams 
Come True With 
Computer Shopper 

Now you can expand your system or 
get a new one at prices you had never 
dreamed possible by taking advantage 
of the thousands of bargains each 
month in COMPUTER SHOPPER. 

COMPUTER SHOPPER is THE 
publication for buying, selling and 
trading new and used micro and mini- 
computer equipment and software. 

• Buy, Sell or Trade 

• 48 Big (11" x 14") pages 

• Over 20,000 readers nationwide 

• Low classified ad rates-only 10c a 
word for subscribers 

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• Money back guarantee 

Double Bonus for New Subscribers 

New subscribers are entitled to a FREE 
20 word classified ad to use for soft- 
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plus a FREE ISSUE (13 months for the 
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price of ONLY $10.00. 
SAVE OVER 50% OFF the single copy 
price of $1.50, Add it up: 

12 issues @ $1.50 $18.00 

One free issue $1.50 

Free 20 word classified ad. . . .$2.00 

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NOW ONLY $10.00. You save $11.50. 

MasterCard or VISA subscription orders only 
Call TOLL FREE FOR FASTEST SER VICE 
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MasterCard or VISA classified ad orders only 

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1-800-327-9926 _„ 

Offer expires 1-31-82 

(((j=CamPUTBR SHCJPP2R 
/p> P.O. Box FI35 • Titusville, FL 32780 
305-269-3211 



Listing 14 continued: 

IFNC \0. NE 
IFNC \0, LT 
IFNC \0, LE 
IFNC \0, GE 
IFNC \0, GT 
RELERR SET 1 ERROR FLAG FOR NEXT SET OF TESTS 

ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 

IFNE RELERR 
RELERR SET 
IFNC \0, CC 
IFNC \0, VC 
IFNC \0, CS 
IFNC \0, VS 

FAIL #* INVALID RELATIONAL OPERATOR — \0 ** 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDM 

# 

* REGTST — 

* THIS MACRO TESTS THE VALIDITY OF THE REGISTER 
« NAME PASSED AS ITS FIRST ARGUMENT. IF THE NAME WAS NOT 

» A VALID REGISTER, 'REGTST' WILL FAIL WITH AN ERROR MESSAGE. 

REGTST MACR 
IFNC \0, A 
IFNC \0, B 
IFNC \0, D 
IFNC \0, X 
IFNC \0, Y 
IFNC \0, U 
IFNC \0, S 

FAIL ** \0 IS NOT A 6809 REGISTER ** 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDC 
ENDM 

■H- 

* IF — 

» THE 'IF' MACRO WILL CAUSE THE STATEMENTS FOLLOWING 

* IT TO BE EXECUTED UP TO THE FIRST 'ELSE' OR 'ENDIF' IF THE 

* CONDITIONAL EXPRESSION IS TRUE. ITS SYNTAX IS: 
# 

* IF <REGISTER NAME>, -^RELATIONAL OPERATOR?--, --CADDRESS EXPRESSION> 

EQ', 'NE', 'LE', 'LT', 



THE VALID RELATIONAL OPERATORS ARE 
'GE', AND 'GT'. 



IF MACR 

IFNE NARG-3 
IFNC \3,L 
FAIL ** 'IF' 
ENDC 

ENDC 

IFC \3, L 
ISLONG SET 1 

ENDC 

REGTST \0 

CMP SO \2 

REL.OP \1 

PUSH *-l-ISLONG 
ISLONG SET 

ENDM 



TEST FOR VALID MACRO CALL. 
MACRO REQUIRES 3 ARGUMENTS ** 



TEST FOR A VALID REGISTER 
GENERATE CMP INSTRUCTION 
GENERATE RELATIVE BRANCH ON CONDITION 
PUSH LOCATION OF FORWARD REFERENCE OFFSET 
ONTO STACK 



ELSE — 

THE 'ELSE' MACRO BEGINS THE STATEMENTS THAT WILL 

BE EXECUTED IF THE CONDITIONAL EXPRESSION OF THE PRECEDING 

'IF' MACRO WAS NOT TRUE. 



ELSE MACR 

IFC \0, L 
ISLONG SET 1 

ENDC 

IFEQ ISLONG 

BRA * 



218 December 1981 © BYTE Publications Inc 



GENERATE BRANCH AROUND STATEMENTS FOLLOWING 
THE "ELSE" 
GENERATE A SHORT BRANCH 

Listing 14 continued on page 220 

Circle 170 on inquiry card. > 



FUTRA COMPANY 

P.O. BOX 4380 - DEPT. B-12 

Torrance, CA 90501 

»13) 328-8951 TWX 910 349-621 1 

□II Free Order Line Outside of Calif. -Please read 

; of press time we were in the process of obtaining a toll free 
number and TWX line. To obtain our latest prices please dial 
421-5006. If you have any trouble reaching us dial 800 
ectory assistance at 800 555-1212 and ask for FUTRA 
3MPANY. Western Union informed us that there may be a 
ange in our TWX number. 



a 



HEWLETT 
PACKARD 




ILL FOR PRICING 



HP-83 HP-85 HP-125 
NOW AVAILABLE 
2903A HP+85/83 16K Memory Module $255.00 



Firmware Enhancements: 

82936A 

82936A ROM Draw 

15001 Mass Stor. 

Plotter/Print 

In/Output 

Matrix 

Adv. Prog. 



15002 
15003 
15004 
15005 



$42 
135 
$135 
$274 
$135 
$126 



Interfaces: 

82937A HP-IB 
82939A Serial (female) 
82939 opt 001 (male) 
Same 002 (crrnt 1p) 
82940A GPI0 
82941 A BCD 



15007 Assembly $127.50 82949A Printer Int. 
HP APPLICATION PACKS $ CALL 



$339 
$339 
$339 
$339 
$421 
$420 
$269 




7225 
aphics Plotter 
$2089.95 



HP 82902M 
Disk Drive 
$1275.00 



K0NAN 



Hfa 



Stop the floppy shuffle! 

New Konan 5". Winchester 

Hard Disk Drive 

Low introductory Pricing 




T o $ „ 2 f 9 «°r. -, I I $129.00 

Z-80 Sofl Card 16K Ram Card 

Wl * CP/M Limited Stock 

en your Apple II computer to a larger world. With the Z-80 Soft- 
rd and 16K RAM Card you can now run CP/M compatible software, 
land your memory for specific application, act as a firmware card 
I much more. If you add any boards to your Apple this year these 
i the ones. 



VIDEX 80 x 24 VIDE0TERM 
AND KEYBOARD ENHANCER 




SCALL 
Videoterm 



SCALL 
Keyboard Enhancer 



ALS "Smartern" 80 column card $295.00 

aintain optimum software compatibility industry wide. By adding the 
deoterm 80 x 24 videoboard and keyboard enhancer your Apple acts 
milar to CRT Terminals on larger systems. Combine this with the 
icrosoft Softcard and you've got some system. 



COMPUTER SUPPLIES: 

M Scotch 5" Diskettes (10) 3M Scotch 8" Diskettes (10) 

744-0 5" SS/SD soft sect. $26 .7400 8" SS/SD $32 

'44-10 5" SS/SO 10 sect. $26 «741-0 8" SS/DD $36 

'44-16 5" SS/SD 16 sect. $26 «743-0 8" DS/DD $44 

'440 5" Head Clean. Kit $29 .7400 8" Head Clean Kit $30 



ISC. 

iilentype Paper (roll) 
i" Vinyl disk sleeves 



$4.50 
$6.95 



•Vinyl Disk Sleeves 



$6.95 



APPLE COMPUTERS 




APPLE II "PIUS" 

16K 
48K 



CALL 



S 



APPLE III 
128K $3255.00 



What can we say except that they're super systems 
and the prices are a steal. 
Apple II 



Disk II w/cont. 

• Disk II 2nd 

• Applesoft Firmware 

• Centronix Printer Int. 

• Communications Card 

• High speed Serial Int. 

• Pascal Language Syst. 

• Integer firmware 

• Parallel Printer Int. 



CALL 
CALL 
S149 
$179 
$179 
$155 
$379 
$149 
$149 



• Hand Controllers 

• Vinyl Carrier 

• Joystick II 

• Graphics Tablet 

• Silentype Printer 

Apple in 

• Information Analyst 

Softwre Pkg 

• Disk II for AIM 

• Silentype Printer III 



$ 27 
$ 33 
$ 45 
$665 
$325 



$345 
$495 
$292 



ADD ON PRODUCTS 



California Computer Systems: 



• 12K PROM/ROM Brd 

• Centronics Cable 

• Calendar Clock 

• Programmable Timer 

• A/D Converter 

• GPIB IEEE 488 



$78 
$30 
$99 
$95 
$95 
CALL 



Mountain Computer Inc. 

• Apple Clock $210 

• Supertalker $255 

• Romplus $131 

• Romwriter $152 

• Romwriter $152 

• X10 Controller $172 

• X10 System $270 

• CPS Multi-function CALL 

Other 

• SSM AIO $159 

• SSMA488 CALL 

• ABT Keypad $115 

• ABT Soft Key $145 

• Novation Cat Modem $155 

• Novation D-Cat Modem $155 

• Novation Apple Cat $319 



• Asynchronous Serial 

• Synchronous Serial 

• Parallel Interface 

• Centronics Interface 

• Arithmetic Proc/Disk 

• Arithmetic Proc/ROM 



• Music System 

• A/D + D/A 

• Keyboard Filter 

• Keyboard Filter 

• Copy Rom 

• I/O Cable Assembly 

• Expansion Chassis 

• Card Reader 



• ABTBarwand 

• TKC Joystick II 

• TKC Keypad II 

• TKC Game Paddles 

• ThunderClock 
Hayes Micromodem I 



$135 
$149 
$ 99 
$111 
$325 
$345 



$465 

$299 

$48 

$48 

$48 

$47 

$649 

$1085 

$175 I 
$ 45 
$149 
$ 27 
$120 
$303 



Hayes Micromodem 100 CALL 



ADD ON SOFTWARE 



Apple Computers: 

• Apple Post 

• Shell Games 

• Apple Bowl 

• DOS 3.3 Update 

• Apple Writer 

• DOS Tool Kit 



Personal Software: 

• Visicalc 3.3 

• Desk Top/Plan II 

• CCA Data Mgt. 



$44 

$28 
$23 
$57 
$65 
$65 



$159 
$165 
$84 



* Stellar Invaders 
■ Apple Plot 
i Adventure 
> AP Music Theory 
' Tax Planner 



> Visiterm 

> Visiplot 

> Visidex 

■ VisiTrend/Visiplot 



Microsoft: (requires Z80 SoflCard & CP/M) 

• Basic Compiler $296 • COBAL Language 

• Assembly Language $94 • Fortran Language 



$23 
$57 
$33 
$47 
$114 



$125 
$147 
$159 
$229 



$562.50 
$149.00 



Peachtree/40: (requires Z-80 SoflCard & 16K RAM Card) 

• General Ledger $195 • Payroll $195 

• Accounts Rec $195 • Inventory $195 

• Accounts Payables $195 • Mail List $195 



Misc: (48K All or AII+) 

• Stoneware 'DB Master' $179 

• BPI General Ledger $315 

• BPI Inventory Control $315 

• BPI Payroll $315 

• BPI Job Cost Sys. $315 



Software Publishing Corp. 

"PFS" $ 87.50 

"PFS: Report" $ 87.50 

MicroFocus "COBOL" $743.00 

MicroPro Wordstar $229.00 



CPM Software Packages - 8" Diskettes 

• Peachtree CPM • Accounting Plus 

• MicroPro 



CALIFORNIA COMPUTER SYSTEM 

The CCS 2210 is a low cost S100, Z80 computer system 
with 64K of memory, disk controller, parallel/serial I/O and 
CPM operating system. 

SCALL 



Separate Components 








• 2200A Mainframe 


CALL 


• 24221 Disk Cntrlr. 


CALL 


• 2810A CPU 


FOR 


• 2718 Par/Ser I/O 


FOR 


• 2065 64K RAM 


PRICE 




PRICE 



ZENITH MONITOR 




12" GREEN 

DATA MONITOR 

$119.00 



Reduce eyestrain with the monitor from the people who say "The 
quality goes In before the name goes on." Excellent for Apple 
II, Apple III and others. 



COMPUTER SYSTEMS 

Call for Lowest Price Possible 




VECTOR 



ALTOS 




ZENITH 



XEROX 



Don't buy anything until you've checked with us. 



VIDEO TERMINALS & VIDEO MONITORS 



Sanyo: 

• 12" Green Monitor 

• 12" B&W Monitor 

• 13" Color Monitor 

• 9" B&W Monitor 

• 9" Green Monitor 

AMDEK: 

• 12" B&W Monitor 

• 12" Green Monitor 



CALL 

FOR 

PRICE 



NEC: 

• 12" Green Monitor 

• 12" Color (RGB) 

• 12" Color Monitor 



CALL 
FOR 



VIDEO TERMINALS: 

• ADDS viewpoint CRT D 

• Soroc 130 HUlit 

• Televideo 



EPSON PRINTERS 
MX-100 

Your price $759.00 

Probably the best buy in a printer this year. Compare features with 
any other and compare price (especially ours). 4 character sizes all 
may be placed into letter quality enhanced mode. Friction and remov- 
able tractor, 9 by 9 to 18 by 18 dot Matrix, logic seeking, and much 
more. Not to mention DOT PL0TTING7GRAFTRAX option built right 
in. WOW! What a printer! 



' MX 80 FT Printer 

i MX 80 Printer 

• MX 70 Printer 

i MX 80 Ribbons 



CALL 
CALL 
CALL 
$14 



• MX Ser. Interface Opt 

• Epson Apple Par. Int. 

• Epson Par. Cable 

• MX-80 or 80/ft Graf- 

traxROM 



$65 
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$20 

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ADDITIONAL PRINTERS 



NEC 

PC 8023 
3510 

DIABLO 

630 

XEROX 

D80 



ANNADEX 

9500 
9501 
9600 
9001 



CHECK OUR LOW PRICES! 



TERMS: Shipping: add 3% for product shipped within continental 
USA via UPS surface (minimum $3.00). If the Order placed is 
prepaid with U.S. funds In the form of check or money order, 
a Total Charge of $3.00 for shipping is all you pay within the 
continental USA via UPS surface. Allow 14 working days for 
personal and company checks to clear. Credit card charges 
limited to $1000. No COD's. FPO, APO or orders outside 
continental USA call or write for shipping charges or add 10% to 
purchase price (any difference will be refunded). California 
residents add 6% sales tax. All offers subject to change or 
withdrawal without notice. 



Circle 337 on inquiry card. 






BIGGEST 

DiSCOUIltS Ever On 

TRS-8CT 



m ■"!« fmWf 




Computers, 

Accessories & 

The Following 

NEW Items 

Hewlett-Packard® 

HP-85 
Personal Computer 

Epson® 

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Home Video System 

Magnavox® 

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• FREE SHIPPING in 48 

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• NO SALES TAX collected 
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• FREE Discount Price List 
available. 



TOLL FREE ORDER NUMBER 

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Fort Worth No. 817/625-6333 

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Pan American 
Electronics 



Sales and Main Office 

Dept. 12 • 1117 Conway Ave. 

Mission, Texas 78572 

NEW Fort Worth Branch 

Dept. 12 • 2912 N. Main St. 

Fort Worth, Texas 76106 



TRS80isaTra 



^nd^olp 



Listing 14 continued: 
ENDC 
IFEQ ISLONG- 1 

LBRA EXBUG 
ENDC 
MCRTMP SET * 
BACK1 

IFEQ BCKLNO 
IFGT <MCRTMP-#-l 1-128 
FAIL ** LONG 'IF' IS REQUIRED ** 
ENDC 



GENERATE A LONG BRANCH. 



FILL IN FORWARD REF. OFFSET IN THE BRANCH 
GENERATED BY AN "IF", "IFTST", OR "IFCC" 



GENERATE A SHORT OFFSET 



GENERATE A LONG OFFSET 



FCB MCRTMP-*-l 
ENDC 

IFEQ BCKLNG-1 
FDB MCRTMP~*-2 
ENDC 

ORG MCRTMP 
POP 

PUSH *-l-ISLONG 
ISLONG SET 
ENDM 



REMOVE POINTER TO "IF" OFFSET FROM STACK 
PUSH LOCATION OF FORWARD REF. OFFSET 
FORMED BY THIS MACRO. 



ENDIF — 

THE 'ENDIF' MACRO IS THE TERMINATING STATEMENT FOR THE 
STATEMENTS CONTROLLED BY THE PRECEDING 'IF' OR 'ELSE' MACRO. 



FILL IN FORWARD REF. OFFSET FROM AN "IF" OR "ELSE" 



ENDIF MACR 
MCRTMP SET * 

BACK1 

IFEQ BCKLNG 

IFGT <MCRTMP-»-l 1-128 

FAIL ** LONG 'ELSE' REQUIRED *# 

ENDC 

FCB MCRTMP-*-l GENERATE A SHORT OFFSET 

ENDC 

IFEQ BCKLNG-1 

FDB MCRTMP-*-2 GENERATE A LONG OFFSET. 

ENDC 

ORG MCRTMP 

POP REMOVE POINTER TO FORWARD REFERENCE FROM STACK. 

ENDM 
###*#####tt ##-&#*-&#•& -a- •&•&-&*•■«■##■&-)*■■«•#$--& -B--H--H- ■«-■&■& *fr #■&####*•-& ###■&■&*$■ #■«■*■## -tut- ■&■«•## *■*■•&* 
# 

* IFTST — 

» THE 'IFTST' MACRO OPERATES LIKE AN 'IF' MACRO EXCEPT 

* THAT IT GENERATES A 'TST' INSTRUCTION INSTEAD OF A 'CMP'. 

* THE SYNTAX IS: 
# 

* IFTST {REGISTER OR ADDRESS EXPRESSIONS {RELATIONAL OP>, 

tt 

* THE VALID RELATIONAL OPERATORS FOR USE WITH 'IFTST' ARE: 'EG', 

* 'NE', 'LT'i AND 'GE' 
# 

IFTST MACR 

IFC S3,L 
ISLONG SET 1 

ENDC 

IFC \2, L 
ISLONG SET 1 

ENDC 

IFC SO, A 

TSTA 

ENDC 

IFC \0, B 

TSTB 

ENDC 

IFNC \0, A 
IFNC \0, B 
TST SO 
ENDC 

ENDC 

RELTST SI 

PUSH *-l-ISLONG 
ISLONG SET 

ENDM 



GENERATE "TST" OF ACC. 



GENERATE "TST" OF ACC. B 



GENERATE "TST" OF A MEMORY BYTE 



GENERATE RELATIVE BRANCH (FORWARD REF. ) 
PUSH LOCATION OF FORWARD REFERENCE. 



IFCC — 

THE 'IFCC MACRO FUNCTIONS LIKE AN 'IF' MACRO, EXCEPT 
IT ONLY GENERATES A 'BRANCH ON CONDITION' INSTRUCTION DIRECTLY. 
THIS IS USEFUL BECAUSE IT ALLOWS THE ASSEMBLER TO GENERATE THE 
LABEL FOR THE BRANCH INSTEAD OF FORCING THAT BURDEN ON THE 
OVER-WORKED PROGRAMMER. THE SYNTAX IS: 



IFCC 



{RELATIONAL OPERATOR> 



THE VALID REALTIONAL OPERATORS ARE: 
'LE'i AND 'LT'. 



'EQ', 'NE', 'GE', 'GT', 

Listing 14 continued on page 222 



220 December 1981 © BYTE Publications Inc 



***** ************************** ********************* 

4MHZ , DOUBLE DENSITY,COLOR&B/W 
GRAPHICS . .THE LNW80 COMPUTER 



COMPARE THE FEATURES AND PERFORMANCE 




When you've compared the features of an LNW80 Computer, you'll quickly 
understand why the LNW80 is the ultimate TRS80 software compatible system. 
LNW RESEARCH offers the most complete microcomputer system at an outstand- 
ing low price. 

We back up our product with an unconventional 6 month warranty and a 10 
days full refund policy, less shipping charges. 

LNW80 Computer $1,450.00 

LNW80 Computer w/B&W Monitor & one 5" Drive $1,915.00 

All orders must be prepaid, CA residents please include 6% sales tax. 
Contact us for shipping charges 

* TRS80 Product of Tandy Corporation. 

** PMC Product of Personal Microcomputer, Inc. 



FEATURES 




LNW80 


PMC-80** 


TRS-80* 

MODEL III 


PROCESSOR 




4.0 MHZ 


1,8 MHZ 


2.0 MHZ 


LEVEL II BASIC INTERP. 




YES 


YES 


LEVEL III 
BASIC 


TRS80 MODEL 1 LEVEL II COMPATIBLE . 


YES 


YES 


NO 


48K BYTES RAM 




YES 


YES 


YES 


CASSETTE BAUD RATE 




500/1000 


500 


500/1500 


FLOPPY DISK CONTROLLER 




SINGLE/ 
DOUBLE 


SINGLE 


SINGLE/ 
DOUBLE 


SERIAL RS232 PORT 




YES 


YES 


YES 


PRINTER PORT 




YES 


YES 


YES 


REAL TIME CLOCK 




YES 


YES 


YES 


24 X 80 CHARACTERS 




YES 


NO 


NO 


VIDEO MONITOR 




YES 


YES 


YES 


UPPER AND LOWER CASE 




YES 


OPTIONAL 


YES 


REVERSE VIDEO 




YES 


NO 


NO 


KEYBOARD 




63 KEY 


53 KEY 


53 KEY 


NUMERIC KEY PAD 




YES 


NO 


YES 


8/W GRAPHICS, 128 X 48 




YES 


YES 


YES 


HI-RESOLUTION 8/W GRAPHICS, 


480 X 192 


YES 


NO 


NO 


HI-RESOLUTION COLOR GRAPHICS 
128 X 192 IN 8 COLORS 


(NTSC), 


YES 


NO 


NO 


HI-RESOLUTION COLOR GRAPHICS 
384 X 192 IN 8 COLORS 


(RGB), 


OPTIONAL 


NO 


NO 


WARRANTY 




6 MONTHS 


90 DAYS 


90 DAYS 


TOTAL SYSTEM PRICE 




$1,915.00 


$1,840.00 


$2,187.00 


LESS MONITOR AND DISK DRIVE 




$1 ,450.00 


$1,375.00 


— 



LNW80 

• BARE PRINTED CIRCUIT BOARD & MANUAL $89.95 



LNDoubler&DOS PLUS 3.3D 

Assembled and Tested w/DOS PLUS 3. 3D $175.00 



The LNW80 - A high-speed color computer totally compatible with 
the TRS-80*. The LNW80 gives you the edge in satisfying your 
computation needs in business, scientific and personal computa- 
tion. With performance of 4 MHz, Z80A CPU, you'll achieve per- 
formance of over twice the processing speed of a TRS-80*. This 
means you'll get the performance that is comparable to the most 
expensive microcomputer with the compatibility to the world's 
most popular computer (TRS-80*)' resulting in the widest soft- 
ware base. 



FEATURES: 



TRS-80 Model 1 Level II Software Compatible 

High Resolution Graphics 

. RGB Output - 384 x 192 in 8 Colors 

. NTSC Video or RF MOD - 128 x 192 in 8 Colors 

. Black and White - 480 x 192 

4 MHz CPU 

500/1000 Baud Cassette 

Upper and Lower Case 

16K Bytes RAM, 12K Bytes ROM 

Solder Masked and Silkscreened 



LNW SYSTEM EXPANSION 

■ BARE PRINTED CIRCUIT BOARD 

AND MANUAL $69.95 

WITH GOLD CONNECTORS $84.95 



The System Expansion will allow you to expand your LNW80, TRS-80*, 
or PMC-80** to a complete computer system that is still totally 
software compatible with the TRS-80* Model 1 Level II. 

FEATURES: 

32K Bytes Memory 

5" Floppy Controller 

Serial RS232 20ma I/O 

Parallel Printer 

Real Time Clock 

Screen Printer Bus 

On Board Power Supply 

Solder Masked and Silkscreened 



LNW RESEARCH 

CORPORATION 

2620 WALNUT ST. 
TUSTIN CA. 92680 



Double-density disk storage for the LNW Research's "System Expan- 
sion" or the Tandy's "Expansion Interface". The LNDoubler™ is 
totally software compatible with any double density software 
generated for the Percom's Doubler***. The LNDoublerTH provides 
the following outstanding features. 

. Store up to 350K bytes on a single 5" disk 

. Single and double density data separation 

. Precision write precompensation circuit 

. Software switch between single and double density 

. Easy plug in installation requiring no etch cuts, jumpers 

or soldering 

. 35, 40, 77, 80 track 5" disk operation 

. 120 day parts and labor Warranty 

*** Doubler is a product of Percom Data Company, Inc. 

DOS PLUS 3. 3D 

Micro Systems software's double density disk operating system. 
This operating system contains all the outstanding features of 
a well developed DOS, with ease in useability. 

KEYBOARD 

LNW80 KEYBOARD KIT $84.95 

The Keyboard Kit contains a 63 key plus a 10 key, P.C. board, and 
remaining components. 

CASE 



LNW80 CASE $84.95 

The streamline design of this metal case will house the LNW80, 
LWN System Expansion, LNW80 Keyboard, power supply and fan, 
LNDoublerTM, or LNW Data Separator. This kit includes all the 
hardware to mount all of the above. Add $12.00 for shipping 

PARTS AVAILABLE FROM LNW RESERARCH 
. 4116 - 200ns RAM 

6 chip set $26.00 

8 chip set $33.50 

16 chip set $64.00 

24 chip set $94.00 

32 chip set $124.00 



LNW80 "Start up parts set" 
LNW80 "Video parts set" 
LNW80 Transformer 
LNW80 Keyboard cable 



LNW80-1 $82.00 

LNW80-2 $31.00 

LNW80-3 $18.00 

LNW80-4 $16.00 



40 Pin computer to expansion cable $15.00 

System Expansion Transformer $19.00 

Floppy Controller (FD1771) and UART (TR1602) . . . $30.00 



ORDERS & I N F0. NO. 714 - 544 - 5744 
SERVICE NO. 714-641-8850 



Circle 224 on inquiry card. 



VISA MASTER CHARGE 
ACCEPTED 



UNLESS NOTED 

ADD $3 FOR SHIPPING 



/HeJ 



Hello. 
This is the APPLE 
talking. The message 
is: Don't byte your 
APPLE. Use COGNIVOX 
to speak to it! 

I am now listening 
for your reply . . . 




Let's face it. Voice I/O is a fascinating and efficient way to 
communicate with computers. And now, thanks to 
VOICETEK, Voice I/O peripherals are easily available, 
easy to use and very affordable. 

If you own an APPLE II computer, COGNIVOX model 
V 10-1003 will enable your computer to understand your 
spoken commands and talk back with clear, natural soun- 
ding voice. 

COGNIVOX can be trained to recognize up to 32 words or 
short phrases chosen by the user. To train COGNIVOX to 
recognize a new word, you simply repeat the word three 
times under the prompting of the system. 

COGNIVOX will also talk with a vocabulary of 32 words 
or phrases chosen by the user. This vocabulary is indepen- 
dent of the recognition vocabulary, so a dialog with the 
computer is possible. The speech output is natural sounding 
since it is a digital recording of the user voice using a data 
compression algorithm. 

For applications requiring more than 32 words, you can 
have two or more vocabularies of 32 words and switch back 
and forth between them. Vocabularies can also be stored on 
disk. 

COGNIVOX V10-1003 comes complete with microphone, 
power supply, software on cassette and extensive manual, 
ready to plug in and use. It plugs into the paddle connector 
and thus it leaves the valuable expansion slots free for other 
peripherals. 

Software provided with the unit includes demonstration 
programs and two voice operated, talking video games! It is 
also very easy to incorporate voice in your own programs. A 
single statement from BASIC is all that is needed to either 
recognize or say a word. 

COGNIVOX can be used as an educational tool, a data en- 
try device when hands and/or eyes are busy, an aid to the 
handicapped, a foreign language translator, a sound effects 
generator, an intelligent telephone answering maching, a 
talking calculator. Using an IEEE 488 interface card you 
can control by voice instruments, plotters, test systems. And 
all these devices can talk back to you, telling you their 
readings, alarm conditions, even their name. 

COGNIVOX V10-1003 costs $249 plus $5 shipping (CA res. 
add 6% tax). Software on diskette (DOS 3.3) with extra 
features to save vocabularies on disk, $19. Order by mail or 
call us at (805) 685-1854, 9AM to 5PM PST, M-F and 
charge it on your MASTERCHARGE or VISA. Foreign 
orders welcome, add 10% for air mail shipping and handl- 
ing. COGNIVOX is backed by a 120 day limited warranty 
against manufacturing defects. 

VOICETEK 

P.O. Box 388, Goleta, CA 93116 



Listing 14 continued: 



TEST FOR VALID MACRO CALL 



IFCC MACR 

IFNE NARG-1 
IFNC \1,L 

FAIL ** ONLY ONE ARGUMENT (A RELATIONAL OPERATOR) ALLOWED ** 
ENDC 

ENDC 

IFC VI, L 
ISLONG SET 1 TEST FOR SHORT OR LONG BRANCH. 

ENDC 

RELCC \0 GENERATE CONDITIONAL BRANCH (FORWARD REF. ) 

PUSH *-l-ISLDNG PUSH LOCATION OF FORWARD BRANCH. 
ISLONG SET 

ENDM 
**»»*#***»**»»#*»*#**#**«•**#***#•»*##**»********#*«■**«•#«■##*«■*****#«**** 
# 

* WHILE — 

* THE 'WHILE' MACRO EXECUTES THE STATEMENTS FOLLOWING 

* IT UP TO THE 'ENDWH' AS LONG AS ITS CONDITIONAL EXPRESSION IS 

* TRUE. THE SNTAX IS: 
# 

* WHILE -^REGISTER NAME>, ^RELATIONAL OPERATORS <ADDRESS EXPRESSION> 



WHILE MACR 
IFNE NARG-3 
IFNC \3, L 



TEST FOR VALID MACRO CALL. 



FAIL ** 'WHILE' REQUIRES 3 ARGUMENTS ** 
ENDC 



ENDC 

IFC \3. L 
ISLONG SET 1 

ENDC 

PUSH * 

REGTST \0 

CMPXO \2 

RELOP \1 

PUSH *-l-ISLONG 
ISLONG SET O 

ENDM 



TEST FOR LONG BRANCH INDICATOR. 



PUSH POINTER TO TOP OF LOOP. 

TEST FOR VALID REGISTER. 

GENERATE CMP INSTRUCTION 

GENERATE CONDITIONAL BRANCH OUT OF LOOP (FORWARD) 

PUSH LOCATION OF FORWARD REFERENCE. 



ENDWH — 



THIS MACRO TERMINATES THE STATEMENTS WITHIN A 'WHILE' 



LOOP. 



ENDWH MACR 

IFC \0, L 
FAIL ** THE 'LONG'' SHOULD BE PLACED ON THE 'WHILE' ** 

ENDC 
MCRTMP SET * 

BACK1 GENERATE OFFSET IN FORWARD REFERENCE OF "WHILE 

IFEQ BCKLNG 
IFGT -((MCRTMP+2)-*-l)-128 
FAIL ** LONG 'WHILE' IS REQUIRED »* 
ENDC 

FCB (MCRTMP+2)-*-l GENERATE A SHORT OFFSET 

ENDC 

IFEQ BCKLNG-1 

FDB <MCRTMP+3)-*-2 

ENDC 

POP 

BACK1 
V A EQU * 

ORG MCRTMP 

IFEQ BCKLNG 

BRA V A 

ENDC 

IFEQ BCKLNG-1 

LBRA V A 

ENDC 

POP 

ENDM 

# 

* REPEAT — 

* THE STATEMENTS BETWEEN A 'REPEAT' AND AN 'UNTIL' MACRO 

* ARE REPEATED UNTIL THE CONDITIONAL EXPRESSION BECOMES TRUE. 
# 

REPEAT MACR 
IFC \0,L 

FAIL ** PLACE 'LONG' ON THE 'UNTIL' ** 
ENDC 

PUSH * PUSH POINTER TO TOP OF THE LOOP. 

ENDM 



GENERATE A LONG OFFSET 



REMOVE POINTER TO FORWARD REFERENCE FROM STACK. 
GET POINTER TO TOP OF LOOP. 



CREATE BRANCH BACK TO TOP OF LOOP. 
GENERATE A SHORT BRANCH. 



GENERATE A LONG BRANCH. 



Listing 14 continued on page 224 



222 December 1981 © BYTE Publications Inc 



Look what's happened to 



HIPL0T 



TM 








It's grown into a complete 

family of quality low cost digital plotters 

with one, six and eight pen models available 



In just a few short years, the HIPL0T 
has become the most popular digital 
plotter among small systems users. With 
a record like that, what can we do for an 
encore? WE'VE INTRODUCED A 
COMPLETE LINE OF HIPL0TS... with 
a model suited for just about every plot- 
ting application. 

The HIPL0T DMP Series is a new 
family of digital plotters with both 
"standard" and "intelligent" models 
available with surface areas of 
Wi"X.ll" (DIN A4) and 11"X17" 
(DIN A3). For the user needing a basic 
reliable plotter, we have the "old stan- 
dard" DMP-2 (&Vz " X 11 ") and the "new 
standard" DMP-5 (11"X17"). For those 
needing a little more capability, there 
are the DMP-3 (8y2"Xll") and the 
DMP-6 (11 "X 17")— both microprocess- 
or controlled and providing easy remote 
positioning of the X and Y axes 
(perfect for the OEM). For 
those who want this in- 



TM HI PLOT and DM/PL are Trademarks 
of Houston Instrument 

* Registered Trademark of Centronics 
Data Corp. 



Yes, they are UL listed!' 



telligence plus the convenience of front 
panel electronic controls, we've provid- 
ed the DMP-4 (8V2"X11") and the 
DMP-7(11"X17"). 

The "standard" plotters come com- 
plete with a RS-232-C and a parallel in- 
terface. The "intelligent" DMP plotters 
accept data from either an RS-232-C or 
Centronics® data source. For the "stan- 
dard" plotters, software is available 
from our ever expanding "Micrographic 
Users Group". The "intelligent" 
HIPLOTs use our exclusive DM /PL™ 
language which minimizes plot software 
to a fraction of that normally associated 
with digital plotting. 

And that's only part of the story. 
Now you can enjoy the advantages of 
multi-pen plotting capabilities with all 
six HIPL0T models. The DMP-2, 3, and 
4 are available in a 6-pen format 



Houston instrument 



— there's an 8-pen option for the 
DMP-5, 6, and 7. So you can now have 
multi- color graphics under program 
control at an affordable HIPL0T price. 

With the new DMP Series, high quali- 
ty digital plotting can now be a part of 
your system. It just doesn't make sense 
to be without this valuable tool when 
there is a DMP plotter with the plot size, 
speed and capabilities that are exactly 
tailored to your specific needs ... and 
your budget. 

Prices for the DMP Series start at only 
$1085 '. Multi-pen plotters start at a low 
$1480'. 

For complete information, contact 

Houston Instrument, 8500 Cameron 

Rd., Austin, Texas 78753. J512) 835-0900. 

For rush literature requests, outside Texas, 

call toll free, 1-800-531-5205. For technical 

information ask for operator #5. In Europe, 

contact Houston Instrument, 

Rochesterlaan, 6 8240 Gistel, 

Belgium. Phone 059/277445. 



GRAPHICS DIVISION OF 

BAUSCH LOMB 




"DMP 2, 3 and A UL listed 
■ DMP 5, 6 and 7 UL listing pending 
* U.S. Domestic Price only. 

Circle 186 to have representative call Circle 185 for literature 



Text continued from page 208: 

• ability to define macros with sub- 
stitutable parameters 

• conditional assembly directives 

• ability to change the value of a 
label 

Most macroassemblers provide these 
three capabilities, and it is surprising 
that structured statements are not 
more widely used. In fact, structured 
statements may be added to an as- 
sembler that has no built-in macro 
facility by writing a preprocessor pro- 
gram to expand the structured macro 
statements. I will discuss this in more 
detail later. 

Evaluation 

A possible objection to the use of 
structured macros is that they in- 
crease translation time for a program. 
However, they may also save time by 
making it easier to read, debug, and 
maintain an assembly-language pro- 
gram. A decrease in errors, and the 
ability to locate these errors more 
quickly, will mean fewer necessary 
translation: and an overall decrease 
in time spent. 



Listing 14 continued: 



UNTIL — 

THE 'UNTIL' MACRO TERMINATES A 'REPEAT' LOOP. IT HAS 
THE SYNTAX: 

UNTIL <REGISTER NAME>, <RELATIONAL OPERATORS <ADDRESS EXPRESSION:: 



UNTIL MACR 
IFNE NARG-3 

IFNC \3, L 

FAIL *# 'UNTIL' REQUIRES 3 ARGUMENTS ** 

ENDC 
ENDC 

IFC \3, L 
ISLONG SET 1 

ENDC 
MCRTMP SET * 

BACK1 
V A EQU * 
ORG MCRTMP 
POP 

REGTST \0 
CMP\0 \2 
RELOP \1 
ORG #-l-ISLONG 
IFEQ ISLONG 

IFGT -<V A-*-l>-128 

FAIL ** LONG 'UNTIL' IS REQUIRED ** 

ENDC 

FCB V A-B--1 
ENDC 

IFEQ ISLONG-1 
FDB V A-#-2 
ENDC 
ISLONG SET 
ENDM 



TEST FOR VALID MACRO CALL. 



TEST FOR LONG BRANCH INDICATOR. 



RETRIEVE POINTER TO TOP OF THE LOOP. 



REMOVE POINTER FROM STACK. 

GENERATE COMPARE INSTRUCTION. 

GENERATE RELATIVE BRANCH TO TOP OF LOOP. 

FILL IN OFFSET OF BRANCH TO LOOP TOP. 



GENERATE A SHORT OFFSET. 



GENERATE A LONG OFFSET. 



It is difficult to express the degree tive, and it must be experienced, 

to which these structured macros ease Macros have been heavily used for 

assembly-language programming, over ten months on a major program- 

The improvement is mainly subjec- ming project, the MC6839 floating- 



50 MHz DIGITAL MEMORY OSCILLOSCOPE 
IN A PERSONAL COMPUTER 



TWO CHANNEL DIGITAL MEMORY 
OSCILLOSCOPE. The Model 85 
provides two signal input chan- 
nels on one board and the time 
base system on a separate 
board. Both vertical channels 
have a full 50 MHz bandwidth. 
Digitization is performed by high- 
speed sample and hold circuitry 
and an eight bit A/D converter to 
ensure high resolution and ac- 
curacy. 

FULLY PROGRAMMABLE. Auto- 
mated measurements were 
never simpler. Programmable 
features such as vertical attenua- 
tion, time base, trigger level, 
AC/DC input and more, make the 
Model 85 a true laboratory and 
factory quality instrument. 



APPLE II* and APPLE II PLUS* COM- 
PATIBLE. The Model 85 Digital 
Memory Oscilloscope plugs 
directly into the Apple II peripheral 
slots. Easily installed-just plug in 
the vertical and horizontal boards, 
attach probe connectors, load 
the software, and you are ready 
to make precision measurements. 

DIGITAL STORAGE. All the conven- 
ient features of digital storage: 
refresh display for easy viewing, 
precision measurements, un- 
limited storage time, signal pro- 
cessing, waveform storage on 
disk, and hard copy output. Now 
with the Model 85 Oscilloscope 
and personal computer combin- 
ation, you can create your own 
sophisticated signal analysis 
system. 



Northwest Instrument Systems, Inc. 

RO, Box 1309 • (503) 279-1434 
Beaverton, Oregon 97075 




NWIS 



A NEW PERFORMANCE STANDARD. 

The Model 85 Digital Memory 
Oscilloscope establishes a new 
performance standard in instru- 
ment systems. Furthermore, priced 
at less than $1,000, it represents 
outstanding value. For more infor- 
mation on the Model 85, send for 
a copy of our product brochure 

"Trademark of Apple Computer Inc. 















































































— ■ 


,,_ 






















, , 


. 


























































m 


180 


w 


IV * 
curi 


C 

or" 


♦ 44 


32 

■ V 


-d 


!6nS 

■ V - 


IB 



NORTHWEST INSTRUMENT 

SYSTEMS, INC. 
MODEL 85 OSCILLOSCOPE 



224 December 1981 © BYTE Publications Inc 



Circle 307 on inquiry card. 



Circle 412 on inquiry card. 



The Performance 




Xon-Glare Green Screen 

— — — Tilt and Swivel 

1 Protected Fields 

8 x 10 Character 
Resolution 

Visual Attributes 

• Code Compatible 

with 912/920 and 

910/950 IkleVideo 

Products 

RS232C Printer Port 

— 25th Status /User Line 

Time of Day 

Character Sets 

(Spanish, German, 

French, English) 



NEW 
925 




Model 925 

Now you can have it all with 
TeleVideo's new 925. Code compatible 
with our 910 and 950 terminals, the 
925, with its 6502 microprocessor- 
based control board can emulate our 
912/920 models while operating at 
speeds up to 19.2K baud. This allows 
you to grow within theTeleVideo 
family of terminals, from the conver- 
sational to the smart. 

The 925, a modular designed unit 
that uses the same power supply, 
monitor, and keyboard as the rest of 
TeleVideo's family, has built-in proven 
reliability and quality from begin- 
ning to end.TeleVideo's P31 non- 
glare, tiltable, green screen and 
detached selectric style keyboard 
make the 925 a comfortable, low 
Stress terminal to use. 

Thei> offer you options; we give 
you standard features like RS232 
printer port, X-on/X-off control, 22 
function keys, user line, 25th status 
line with setup mode, local duplex 
edit modes, and many more. 

Nationwide service is available 
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point ROM (read-only memory) and 
they have proved indispensible for re- 
ducing the complexity of that pro- 
gram to manageable proportions. 

Extensions 

An old adage states that no pro- 
gram is ever complete, and it is true 
that several other structured macros 
could be easily added to the existing 
set. Four straightforward additions 
would be to create TST and CC forms 
of the WHILE and UNTIL macros. A 
FOR loop, such as that in Pascal, 
would be useful, but would present a 
substantially more formidable imple- 
mentation problem. At present, the 
equivalent of a FOR loop can be 
created out of a WHILE... ENDWH 
structure. 

Macros in Other Languages 

While facilities for subroutines are 
almost universally available, facilities 
for using macros are available in rela- 
tively few languages. Assembly lan- 
guages are an exceptional case in that 
most assemblers provide at least a 
rudimentary mechanism for defining 
and using macros. As a result, the 
power and generality of macros are 
not widely appreciated. 

Two notable exceptions lift macro 
programming out of the realm of as- 
sembly language. One is a book by 
Brian W Kernighan and P J Plaguer, 
entitled Software Tools (Addison- 
Wesley, 1976). Macros are used to 
add structured control statements to 
FORTRAN, which has resulted in a 
new language called RATFOR (Ra- 
tional FORTRAN). Software Tools 
uses RATFOR to present a series of 
increasingly complex programs that 
culminate in a macroassembler pro- 
gram. This macroassembler takes a 
RATFOR program as input and 
creates an equivalent FORTRAN pro- 
gram, which may then be translated 
and executed as usual. RATFOR is an 
excellent example of a high-level lan- 
guage made more structured through 
the use of macros. 

The second exception is the C 
programming language, which uses a 
simple macroassembler as the first 
step in translating C programs. 
Macro expansion constitutes the first 
I step in translating a computer pro- 



226 December 1981 © BYTE Publications Inc 



Circle 354 on Inquiry card. 



You may be holding 
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you could ever own... 
in the Palm of Your Hands 





TITLE: "THE PROGRAM WRITER/REPORTER® " 

Enables ANYONE to write complete, running, debugged BASIC LANGUAGE Pro- A. No, the resulting programs will be sophisticated and extremely fast operating, 

grams in 35 to 40 minutes with NO PRIOR PROGRAMMING KNOWLEDGE OR For example, should you create a mailing list or inventory program, the time for any 

ABILITY. record to be retrieved and displayed from a full disc would take a maximum of 

IF you are one of the many who bought a microcomputer in the belief that with 1 second, 

just a little studying you could write your own programs, you now know that you Q. Must the programs produced conform to a pre-determined format and file 

can't. length? 

IF you, as a businesman, thought you could have stock software modified at a A. No, you determine format and file size to fit your requirements. You may have as 

reasonable cost with reasonable results, you know that's not possible either. many as 300 fields or as few as 1. 

IF you are a hobbyist getting tired of the untold hours it takes to write a program, Q. Can I develop my own business programs? 

only to find it takes more hours to debug than to write. A. For the most part, yes. 

IF you are a skilled programmer you don't have to be reminded of the repetitious Q. What are the limitations? What programs can I produce with THE PROGRAM 

time spent on each new application. WRITER/REPORTER"' ? 

IF you have left your micro-computer sitting somewhere gathering dust . . . meet A. Your own ingenuity and hardware limitations. 100's of different programs. 

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Circle 428 on Inquiry card. 



gram, and in C, as well as RATFOR, 
the macroassembler consists of a sep- 
arate program that is run before the 
main translator program. So if you 
possess a macro preprocessing pro- 
gram, you need never program in a 
language that lacks structured control 
statements. 

I cannot leave the subject of macros 
without including one final comment 
about the generality of their useful- 
ness. Macros, acting as they do at 
translation time, are really transfor- 
mations of written text, and that text 
need not be a computer program. For 
example, a set of macros could be 
used to expand into standard head- 
ings and endings for writing business 
correspondence. 

A Step in the Right Direction 

The title of this article was chosen 
to imply a sense of progress not yet 
completed. The structured assembly- 
language statements presented here 
are only the first step in spreading the 
benefits of structured programming 
to languages that are currently not 
well structured. Control structures 



are easy to implement and can be 
added to even the most primitive pro- 
gramming language, but there are 
other aspects of structured program- 
ming that have yet to be explored in 
connection with assembly language. I 
will briefly examine two of these 
aspects: data structuring and subrou- 
tine structuring. 

High-level languages such as Pascal 
and C provide atomic data types, 
such as numbers and characters, 
which can be built up into data 
structures. A data structure is a com- 
plex combination of data types re- 
ferred to by a common name, the 
subparts of which can be accessed in a 
consistent manner. An array is just 
such a data structure having every 
element of the same data type. 

The most general form of a data 
structure contains any number of ele- 
ments of differing types (called a 
"record" in Pascal and a "structure" 
in C). Is it possible to add similar data 
structures to an assembly language in 
the same way that control structures 
were added? At present, the answer 
appears to be no. 



What kind of indexing program 
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One advantage offered by high- 
level languages over assembly lan- 
guages is the association of a specific 
type to each data element. Part of the 
reason modern compilers are more 
complicated than assemblers stems 
from the type-checking that occurs as 
each use of a data item is being 
translated. Type-checking is too com- 
plex to be performed by a macroas- 
sembler; it could be added to an as- 
sembly language only by performing 
an extensive rewrite of the assembler 
program. 

The languages PL/M, from Intel, 
and MPL, from Motorola, represent 
attempts at marrying data structures 
and other high-level concepts to as- 
sembly-language programming, but I 
am not sufficiently familiar with them 
to evaluate their effectiveness. 

Subroutine structuring partakes of 
particular aspects of both structured 
control and structured data, but it is 
such an important (and complex) 
aspect of computer languages that it 
deserves separate consideration. Sub- 
routine control structuring consists of 
nothing more than the run-time ex- 
pansion examined earlier. Subrou- 
tines appear in a program much as the 
other control structures: they are 
made up of structuring statements 
that bracket a block of assembly-lan- 
guage statements, and that block of 
statements may itself contain nested 
subroutine calls. 

However, more than control is 
passed to a subroutine. Data in the 
form of subroutine parameters is also 
transferred. In standard BASIC, all 
the data used in a subroutine is global 
(ie: it exists both inside and outside 
the subroutine). Languages like 
Pascal and C allow subroutines to 
have parameters and data that are 
local to the subroutine and exist in 
computer memory only while the sub- 
routine is being executed. 

' The MC6809 and MC68000 micro- 
processors both contain machine in- 
structions that aid in passing param- 
eters to subroutines and in creating 
data local to a subroutine. The devel- 
opment of methods that win extend 
assembly languages in order to ex- 
press these subroutine structures pro- 
mises to be a fruitful area for further 
work.H 



228 December 1981 © BYTE Publications Inc 



Circle 324 on inquiry card. 



MIKBUG and the TRS-80 

Part 1: A Cross- Assembler 
for the Motorola 6800 



Robert Labenski 

145 Steele Rd 

West Hartford CT 06119 



I've always appreciated my TRS-80 Model I, largely 
because it's so easy to use. Recently, however, this ap- 
preciation heightened considerably when I bought the 
Motorola 6800 evaluation kit (MEK 6800 Dl). That's 
when I realized I had become spoiled by the sophistica- 
tion and ease of use of the Radio Shack machine. 

The Dl comes with a minimum of programming sup- 
port: a machine-language monitor called MIKBUG. It 
does a good job as a monitor, but after two years of using 
a disk-based editor/assembler, who wants to hand-as- 
semble object code and load it 2 bytes at a time7 

This prompted me to write a full programming system 
for the Dl kit. The programs run on the TRS-80, which is 
connected to the Dl as a terminal. As far as the Dl is con- 
cerned, the TRS-80 is nothing more than an I/O (in- 
put/output) terminal; little does the Dl know that the 
TRS-80 is also serving as a cross-assembler with file 
capabilities, a downloader, and a debugger! 

To use this programming system, you need: 

• the Motorola MEK 6800 Dl, or any other 6800-based 
system running MIKBUG 

• a TRS-80 Model I with 48 K bytes of programmable 
memory, one disk drive, and an RS-232C interface 

• connecting cables from the TRS-80 to the Dl via their 
RS-232C channels 

You don't need the disk drive if you rewrite all the file 
I/O sections for tape instead of disk. 



I've divided this article into two parts. Part 1 describes 
the editor and cross-assembler — the program that inputs 
your 6800 source code and outputs 6800 object code. 
Both source and object code are saved on disk. Part 2, in 
next month's BYTE, describes the downloader (the pro- 
gram that transfers the 6800 object code into the correct 
memory locations in the Dl system) and the debugger, a 
function that allows your TRS-80 to act like an enhanced 
Dl terminal. 

The Editor and Cross-Assembler 

The editor and cross-assembler program is written in 
TRS-80 Disk BASIC (see listing 1). 

When I write programs that have several commands 
associated with them, I program a help screen. Figure 1 
(on page 242) is a copy of this screen. It contains all the 
commands needed to make the program usable. 

When the prompt, "READY*", is displayed, the 
following general-purpose commands may be used: 



H 
F 



R 
C 

S 



Display the help screen of figure 1. 
Request for file I/O. You are asked whether 
you wish to save or load and what files you 
wish to use. 

Clear the system and restart the assembler. 
Assemble the source code stored in the system. 
Display the symbol table used to resolve ad- 
dresses encountered during an assembly. 

Text continued on page 242 



December 1981 © BYTE Publications Inc 229 



Listing 1: The editor and cross-assembler program written in TRS-80 Disk BASIC. 



100 
1 1 § 

120 
139 
140 
150 
160 
170 

1S0 

190 

210 
229 

'0 

250 
60 
70 
280 
290 

300 

310 
326 
330 



MINI 6S00 COMPILER FOR THE TRS-80 
ROBERT LABENSKI NEST HARTFORD COHN 



CLEAR 12000 
OIMS$(208) 
OIMNQ$< 100) 
DIHOP$< 100> 
DINBR$< 16) 
0IM08$< 2O0 ) 
DIMhD<200> 
DINLA$< 1H0) 
DIMLN< 100) 
DIMhR( 100) 



■DEFINT A-Z 
'SOURCE DATA 

'OPERATIONS N/ IMPLIED OPERANDS 

' FULL OPCODES 
• BRANCH INSTRUCTIONS 

' OBJECT 
' ADDRESS 

' SOURCE LABELS LC=IHDEX 
' LINE # OF LABELS 
' LINES NEEDING ADDRESS RESOLUTION AC=INDE> 



1 200 



GOTO OF CTRL 



Lh 



GOSUB 1 550 : GO TO 

RESTORE 'COMPILE 

LC=0 •' AC-0 •' CD-B 

IF OT THEN 340 ELSE 

CD=0:FOR X=1T0LEN(A$):Y 

IF Y<=57 AND Y>=48 THEN 

IF Y>64 THEN Y=Y-55 

CD= 1 6tC0 + Y ■• HEX T • RE TURN 

F0RA=8 T01 OB •• READ N0$< A ) ■■ IF N0$( A 

FOR A=0TO10O i READOP$( A ) ' IF0P$( A ) 

FOR. A=0 TO 15: READ BR$(Ah'NEXT 



1 : GOT 03 10 

ASC(MID$(A$, 

y=Y~4o 



>" END "THEN NEXT 
"EHD"THENNEXT 



Listing 1 continued on page 234 



Peachtree Software' 'Word Processing Is A 

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A. 



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"nee you've used any Peachtree 
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Peachtree Software reflects years of 
development, refinement and user test- 
ing. That's why there are more than 
20,000 Peachtree Software packages in 
use. To get yours, see your nearest dealer or call, 800-835- 
2245, ext.35 (in Kansas, 800-362-2421, ext. 35). 




The Very Best "Off-The-Shelf "Software IsW-The-Tree: 




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Peachtree Stilt ware, Magic Waml. Maitic Spell, and Stiles Trackers are trademarks of Peachtree Software, Incorporated. 



230 December 1981 © BYTE Publications Inc 



Circle 342 on inquiry card. 



libu may be in a position to justify an 
airplane and not even know it. -^ 



The Beechcraft Bonanza A36TC can carry 6 people at speeds up to 246 mph. 



To find out, take this 
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4- Have you ever lost business 
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your top management 
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5. Do you often travel 
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Yes D No □ 

6. Do your salesim 
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on the road 
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If you answered yes to any of 
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trouble justifying a Beechcraft com- 
pany airplane. To your accountants. 
Your board of directors. Or your stock 
holders. Because a Beechcraft 
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ductive travel. 



The Beechcraft Baron E55. A 6-seat twin 
that combines speed, fuel-efficiency 
and comfort. Up to 239 mph. 





It means one of your most valu- 
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Our free Management 
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dollars and capital recovery. And the 
more you travel, the more sense it 
makes. 

Especially when your Beech 
dealer makes owning an airplane 



so simple. He has a unique plan for 
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you. Maintenance, scheduling, up- 
keep, helping to find pilots, what- 
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r -_______ ________________ 

Send for your free 1981kit. 

If you answered 
yes to any of the quiz 
questions, write us at 
Beech Aircraft Corpo- 
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AskforDel Chitwood. byt 1201 

© Member Genera! Aviarion Manufacturers Association 




I 




echcrait 



For free information on (earning to fly or upgrading your flying skills, plus 

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HEATH/ZENITI 
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The Heath/Zenith 25 Printer is a heavy-duty, high-speed, 
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For your custom programs. Microsoft languages are avail- 
able in BASIC (compiler and interpreter), FORTRAN and 
COBOL. Or learn to write and run your own programs with 
special self-study programming courses for Assembly, 
BASIC, Pascal or COBOL. 

Free demonstration awaits you at 
your Heathkit Electronic Center 

Pick the store nearest you from the list at right. And stop 
in today for a demonstration of the new Heath/Zenith System. 
If you can't get to a store, send $1 .00 for the new Zenith 
Data Systems Catalog of assembled commercial computers 
and also receive free the latest Heathkit Catalog. Write to 
Heath Co., Dept. 334-844, Benton Harbor, Ml 49022. 




Visit Your Heathkit Electronic Center * 

where Heath/Zenith Products are displayed, sold and serviced. 



PHOENIX, AZ 

2727 W. Indian School Rd. 
602-279-6247 

ANAHEIM, CA 
330 E. Ball Rd. 

714-776-9420 

CAMPBELL, CA 

2350 S. BascomAve. 
408-377-8920 

ELCERRITO, CA 

6000 Potrero Ave. 
415-236-8870 

LA MESA, CA 

8363 Center Dr 
714-461-0110 
LOS ANGELES, CA 

2309 S. Flower St. 
213-749-0261 

POMONA, CA 

1555 N. Orange Grove Ave. 
714-623-3543 

REDWOOD CITY, CA 

2001 MiddlelieldRd. 
415-365-8155 

SACRAMENTO, CA 

1860 Fulton Ave. 
916-486-1575 

WOODLAND HILLS, CA 

22504 Ventura Blvd. 
213-883-0531 
DENVER, CO 
5940 W. 38th Ave. 
303-422-3408 

AV0N.CT 

395 W. Main St. (Rt. 44) 

203-678-0323 

HIALEAH, FL 

4705 W. 16th Ave. 

305-823-2280 

PLANTATION, FL 

7173 W.Broward Blvd. 

305-791-7300 

TAMPA, FL 

4019 W. Hillsborough Ave. 

813-886-2541 

ATLANTA, GA 

5285RoswellRd. 

404-252-4341 

CHICAGO.IL 

3462-66 W.Devon Ave. 
312-583-3920 

downersgrove.il 

224 0gdenAve. 
312-852-1304 
INDIANAPOLIS, IN 

2112 E. 62nd St. 
317-257-4321 



MISSION, KS 

5960 Lamar Ave 
913-362-4486 

LOUISVILLE, KY 

12401 ShelbyvilleRd. 

502-245-7811 

KENNER.LA 

1900 Veterans 

Memorial Hwy. 

504-467-6321 

BALTIMORE, MD 

1713 E. Joppa Rd. 

301-661-4446 

ROCKVILLE.MD 

5542 Nicholson Lane 

301-881-5420 

PEABODY, MA 

242AndoverSt. 

617-531-9330 

WELLESLEY, MA 

165 Worcester Ave. 

617-237-1510 

DETROIT. Ml 

18645 W. Eight Mile Rd 

313-535-6480 

E. DETROIT, Ml 

18149 E Eight Mile Rd. 

313-772-0416 

HOPKINS, MN 

101 Shady Oak Rd. 

612-938-6371 

ST. PAUL, MN 

1645 White Bear Ave. 

612-778-1211 

BRIDGETON.MO 

3794McKelveyRd 

314 291-1850 

OMAHA, NE 

9207 Maple St 

402-391-2071 

ASBURYPARK.NJ 

1013 Stale Hwy. 35 

201-775-1231 

FAIR LAWN, NJ 

35-07 Broadway (Rt. 4) 

201-791-6935 

AMHERST, NY 

3476 Sheridan Dr. 

716-835-3090 

JERICHO, L.I. NY 

15 Jericho Turnpike 

516-334-8181 

ROCHESTER, NY 

937 Jefferson Rd. 

716-424-2560 

N.WHITE PLAINS, NY 

7 Reservoir Rd. 

914-761-7690 



CLEVELAND, OH 

28100 Chagrin Blvd. 

216-292-7553 

COLUMBUS, OH 

2500 Morse Rd. 

614-475-7200 

TOLEDO, OH 

48 S. Byrne Rd 

419-537-1887 

W00DLAWN.0H 

10133 Springfield Pike 

513-771-8850 

OKLAHOMA CITY, OK 

2727 Northwest 

Expressway 

405-848-7593 

FRAZER, PA 

630 Lancaster Pike 

f Rt. 30) 

215-647-5555 

PHILADELPHIA, PA 

6318 Roosevelt Blvd. 

215-288-0180 

PITTSBURGH, PA 

3482 Wm. Penn Hwy 

412-824-3564 

WARWICK, Rl 

558 Greenwich Ave. 

401-738-5150 

DALLAS, TX 

2715 Ross Ave 

214-826-4053 

HOUSTON, TX 

1704 W. Loop N. 

713-869-5263 

SAN ANTONIO, TX 

7111 Blanco Road 

512-341-8876 

MIOVALE.UT 

58 East 7200 South 

801-566-4626 

ALEXANDRIA, VA 

6201 Richmond Hwy. 

703-765-5515 

VIRGINIA BEACH, VA 

1055 Independence Blvd 

804-460-0997 

SEATTLE, WA 

505 8th Ave. N. 

206-682-2172 

TUKWILA.WA 

15439 53rd Ave. S. 

206-246-5358 

MILWAUKEE, Wl 

5215 W. Fond du Lac 

414-873-8250 

' Units of Veritechnology 
Electronics Corporation in 
the U S. 



Prices and specifications subject to change without notice 



HEATH/ZENITH 



Your strong partner 



Listing 1 continued: 

349 OK=l'MftIN COMPILE LOOP 

350 FOR ft=9T0N-l 

360 IF LEFT$<S$< ft); !)="*" 0B$( ft )=" " ■ ftD( ft >=CD 'GOTO 450 
370 -IF MIO$<S$(ft>, 7.. 1 )<>••&" THEN 406 
3S0 ftD(ft)=CO 

399 QB$<ft)="" : FOR B-8T03B' ft$=NID$(S$( ft .>..£?, 1 > > IF ft$="&" THEN 456 ELSE Y=ftSC(ft$ 
):v=0:ft$="" .-GOSUBS50 ^ 08$< ft >=0B$< ft )+ft$ ; C£i=CD+l i NEXT 

400 ft$=NID$<S$(ft>, 7.-4) = IF LEN(ft$>=3 ft$=--ft$+" " 

410 IF ft$="ORG " THEN ft$=HID$ ( S$ (ft >.. 15, 4 ) ■ 0B$< ft )=" " GOSUB270 'GOTO 459 

420 IF LEFT$<S$(ft) / 4)<>" " THEN Lft$( LC)=LEFT$( S$( ft .>, 4 ) ■ LN< LC )=ft ■ LC^LC-1 

439 IF LEFT$(ft$,l>="B" GOTO 710 

449 IF LEN(S$(ft>)< 15 GOSUB 539 ELSE GOSUB 699 
459 NEXT ft 

469 IF SW=l? THEN 529 
479 FOR h=0 TO ftC-1 

450 FOR B=9T0LC-1 ■ IF RIGHT$< 0B$( ftR( ft > ).■ 4 ><>Lftt( B ) THEN NEXT 

499 IF MIO$(S$(ftR(ft>), 7.. 1 >="B"THEN X=fiD< AR( 'A >) ■ Y=fiD< LH( B > > ■• P)D< 160 >=Y-< X+2 > •• C=18 
9 ■ GOSUB940 ■ 0B$( ftR( ft ) )=L EF T$< 0B$< ftR( ft ) ) .. 2 HRIGH T$<h$.- 2 ) ■ G0T051 9 
590 C=LN( B ) • GOSUB940 ■■ 0B$( ftR( ft ) )=LEFT$( 0B$( ftR( ft ) )., 2 >+ "B"+ft* 
510 NEXT ft 

529 RETURN 

530 'IMPLIED OPERftNDS 

540 IF NID$(S$<ft>..7,l)="$" 9Bt(ft>=RIGHT$<S$<ft>,LEN<S$<ft>>-7: 



ftB( ft )-CD •' CD=CB+( 



LEN(S$(ft. 



. y i .•• ■:• • 



RETURN 



550 FOR B=0 TO 180 

560 IF LEFT$(N0$(B:^4)="END" THEN OB$<ft)="tERR$" 'RETURN 

570 IF LEFT$(NQ$(B>..4)=ft$ THEN 0B$< ft >=RIGHT$< N0$< B h 2 ) ■■ ftOi ft >=CB ■ CB=CD+1 •■ RETURN 

5S0 NEXT 

5$d ' ft$=R IGHT$< S$< ft > > LEN< S$< ft >-S > 

600 ' OTHER OPS Listing 1 continued on page 236 



Computers may simplify your business, 
but it isn't always simple to choose one 



CALL FOR PRICE 




CROMEMCO System One 



NBN 



• Z80-A RAM • Small size • 780K Disk Storage 
• CRT and Printer interfaces • Eight S-100 card 
slots allowing expansion with: —color graphics 
—additional memory —additional interfaces for 
telecommunications data acquisition, etc. 



QANTEX* 
6000 Printer 



• 150 characters per 

second • 136 columns 

per line • parallel or serial Parallel 

interfaces • 9 x 9 dot ma- Serial 

trix • 400 million character Model 6010 

printhead • upper & lower 

case with descenders 




$1295.00 
1359.00 
1399.00 



MORE SPECIALS 

BALLY Arcade Computer $279.95 

MATTEL Intelevision Computer 279.95 

N0RTHSTAR64KDD 3395.00 

BOSHEI19"ColorTV 329.95 

ATARI 800 w/ 410/ 32K 899.95 

T.I. 810 Basic R0 1359.00 

•Registered Trademark of North Atlantic Industries, Inc. 



, We carry a full line of Cromemco, Northstar, Epson, Texas Instruments, Atari, Bally, Hazeltine, Adds, Qantex, Malibu and others 

A 



SYNCHRO-SOUND International, Inc. 



COMPUTER AND VIDEO SYSTEMS CENTER 

Where the computers are cold and calculating. But the people aren' 



1550 Northern Blvd., Manhasset, N.Y. 11030 
516-869-8535 TOLL FREE: 800-645-3820 

Master, Visa, American Express 



234 December 1981 © BYTE Publications Inc 



■-♦•4,, -^ 




Nobody's 

better protection 

than The Marshal 

in Winchester territory. 

You got yourself a Winchester disk drive 

with all that large system power. Great! 

But trying to utilize your floppy drive for backup just isn't working. 

And bit-streaming tape cartridge drives offers no practical protection, 

because the usual need is archival storage and replacement of 

individual files lost through operator error; but the streamer 

tape data cannot be reconstructed by separate files easily. 

Enter The Marshal to your rescue. 

He's the only match in speed, 

capacity, and capability for your Winchester. 

As Thomas S. Stellinger, Manager of Marketing Literature 

with Computer Service Systems Network, Inc. stated in 

InfoWorld, "Intelligent tape subsystems, combining the 

1/2-inch tape cartridges with file-oriented software 

offers the best solution to hard disk backup.. .a utility 

program. ..allows the user to save every file in the 

system, as well as to restore individual files by name." 

The Marshal from TKS Corporation. 

The only complete hardware/software protection 
device for computer hard disk systems. 

The Marshal follows commands, 
is fast, and thinks for himself. 

Formatted capacity is 13.4 megabytes. The transfer 

rate is 192,000 bits per second. And he can 

determine which files have been updated since last 

saved, in order to recopy only those specific files — 

saving time. Then records the date he made the copy. 

Perfect protection for the perfect price. 

Your OEM Distributor can introduce you 

to a rack mount unit or a table top console 

for much less than you'd guess. 

Take this ad to your dealer today, save a heap of 

money off the regular price, and get the best 

protection available in Winchester territory. 

The Marshal from TKS Corporation would 

sure be happy to help you. 1-800-327-2848. 

In Florida or 

outside the U.S. 

305-593-0010. 




■WINSET FINE ADVERTISING 
/ 



TKS Corporation 

8472 NW 56 Street, Miami, FL 33166 

Circle 415 on inquiry card. 



Listing 1 continued: 

618 RD<R)=CO 

628 FOR B=8T0188 

63d IF LEFT${0P$<B).>4)="END" THEN 0B$( ft )="tERRt ! ' 'RETURN 

640 IF LEFT$(0P$(B>,4)OR$ THEN NEXT 

658 IF MI0$(S$(R), 15,2>="X, " THEN 0B$( R )=!1IQ$< QF$< B >, 18, 2 > + <1ID$< S$< ft ).■ 17, 2 ) ■ CD= 

CD+2- RETURN 

660 IF NID$(S$(R), 15, 1 )="#" THEN 0B$( ft >=MID$( 0P$( B ), 6 , 2 > ■• QB$(fi )=0B$< f))+NID$( S$ 

(ft), 16, 2 > •• CB=CQ+2 ■■ B$=LEFT$( 0B$( R >.- 2 ) •• IF B$0"SC"ftNDB$<>"CE"ftNDB$0"SE" THEN FE 

TURN ELSE CD=CD + 1 ■■ 0B$( ft )=0B$( ft )+RIGHJ $< S$( R >, 2 >• RETURN 

670 IF MIO$(S$(h), 15,1)=" " THEN 0B$< ft )="tERRt" •■ RETURN 

680 IF MID$(S$<R>, 15, 1 )="$" THENR$=MID$(S$(R>, 16,4) ELSE R$=MID$( S$( R >, 15, 4 > ■■ RR 

<RO=R:RC=RC+l :SH=1 :R$=h$+STRING$<4-<LEN(R$>), " " ) 

698 IF LEN<R$)=4 THEN 0B$( h )=MID$( 0P$( B >, 12, 2 > ■ 0B$( R >=0B$< R )+R$ ■■ CD=CB+3 ■• RETURN 

708 0B$( R )=MID$( 0P$( B),S,2): 0B$( R )=8B$( R >+R$ ■ CD=CD+2 ■ RETURN 

718 'BRANCH INSTRUCTIONS 

728 FOR B=8T015:IF LEFT$( R$, 3 )=LEFT$( BR$( B ), 3 >THEN 748 ELSE NEXT 

738 QB$(R)="tERRt" --GOTO 458 

740 0B$< R >=RIGHT$( BR$< B ), 2 ) •" RD< R )=CD < C0=CD+2 ■ RR( HC )=R • RC=RC+1 

750 R$=MID$<S$(R>, 15, 4 > : 0B*< R >=QB$< R >+R$+STRING$>: 4-LEN< R$ >, " " >:SN=1 'GOTO 458 

768 OK=0 •• LC=0 ■• RC=8 ' SOURCE COLLECTION I , IKK 

776 IF LEN(R$)>1 THEN 810 

7S8 PRINT N:TRB(lB)i >LINEINPUTS$< N) 

790 IF SS(N)="" RETURN 

SO0 N=N+1 'GOTO780 

810 R=UhL(RIGHT$(r$,LEN(h$>-1 )) < IF R>N THEN 780 

S20 PRINT RjTRB(ld).: 'LINEINPUTRi- 

S30- IF R$="" RETURN 

840 FOR B=N+i TO h STEF-1-IF B=0 THEN S50 ELSE S$(B)=S$(B-1 ) ■■ NEXT 

Listing 1 continued on page 238 



BREAKTHROUGH! 



View and edit many 
files simultane- 
ously. 

Draw diagrams as 
easily as typing 
text. 



Cut text from one 
window and paste 
it into another. 




Automatic 
Horizontal and 
Vertical scrolling. 

Create your own 
commands for 
your applications. 

Automatic 
memory manage- 
ment of large files. 

Compare, contrast , 
review or analyze. 



A MULTI -WINDOW TEXT EDITOR FOR UNDER $200. 



Imagine this kind of productivity: Your 4 favorite files right 
before your eyes on the screen of your CRT. 

Divide the screen of your CRT into any combination of 
horizontal and vertical windows, each with its own 
workspace. Or, windows can share a workspace — so you 
can edit different parts of the same file. 

You get true on-screen editing, plus the ability to add or 
delete any of 10 windows, at any time, anywhere on the 
screen. 

Using CP/M compatible files and simple, easy to remember 
commands, THE ELECTRIC BLACKBOARD" has 
functions to satisfy the needs of the most demanding 
professional computer scientist. Yet THE ELECTRIC 
BLACKBOARD" can be used just as productivly by the 
novice within minutes. A step-by-step Learning Guide, 



designed for the novice, will guide you gently through the 
learning process. 

Unleash the extraordinary power and flexibility of THE 
ELECTRIC BLACKBOARD™ on your Z80-based micro- 
computer today. 

Requires 48k CP/M or CDOS, Z80 processor.and CRT with cursor 
addressing. Distributed on SSSD 8" diskette. Includes reference 
manual, learning guide, and quick reference card. Price: $198, 
manuals only: $30. 

Call or write for more information: 

SANTA CRUZ SOFTWARE SERVICES 

1711 Quail Hollow Road , Ben Lomond, CA 95005 
(408)336-2170 

CP/M is a trademark of Digital Research CDOS is a trademark of Cromemco 
Z80 is a trademark of Zilog 



236 December 1981 © BYTE Publications Inc 



Circle 373 on inquiry card. 



EXCITING NEWS FOR TRS-80" MODEL III USERS! 



Standard & Poor's unique software and 

data system— STOCKPAK— can help you 

manage your investments like 

a Wall Street Professional! Now for 

TRS-80 Model I and Model III users too! 



STOCKPAK not only delivers a "stand-alone" Port- 
folio Management System but also gives you the soft- 
ware for Standard & Poors monthly Common Stock 
Data Service (available to TRS-80 owners on a sub- 
scription basis). With STOCKPAK and the Data Ser- 
vice you command one of the most powerful and 
versatile investment tools available. 

Here's How STOCKPAK Will Help You: 

A 900 COMPANY DATA BASE SERVICE 

Monthly Data Service subscribers receive a diskette 
containing 30 vital financial items on 900 of the most 
widely traded stocks (S&P "500" and 400 NYSE, ASE 
and OTC issues). Accompanying this monthly diskette 
is an Investor's Newsletter highlighting important fi- 
nancial news and investment strategies, with sugges- 
tions for maximizing the usefulness of the system. 



STOCKPAK SELECTION SYSTEM 

The heart of STOCKPAK is a powerful, analytical 
stock selection tool which enables investors to choose 
stocks which meet their investment criteria. For exam- 
ple, you may wish to select only those oil and gas stocks 
with price/earnings ratios of less than 7 and yields of 6% 
or more. Once a group of stocks has been selected, you 
can store it as a separate data file for continuing use. 

REPORT WRITER 

You can define the report formats you would like to 
see on those stocks meeting your investment objec- 
tives. Hundreds of calculations and ratios that you 
define can be sorted, averaged or totalled, and dis- 
played on video screen or optional printer. 



rr^ TBS-BO 



« POOR'S 
STOCKPAK 

PORTFOLIO 
MAfyAOEMEftJT 


si* 










\ 










^^^^^™ 





iJasgA^sfrs^l 



PORTFOLIO MANAGEMENT SYSTEM 

Now you can effectively evaluate and manage your 
own stock portfolio of up to 100 securities with as many 
as 30 transactions for each. You can record "buy" and 
"sell" transactions, price and dividend information and 
stock splits for instant retrieval, for record keeping and 
tax purposes. You can measure actual performance or 
create hypothetical situations to help you make "buy" 
or "sell" decisions. 

HOW TO ORDER STOCKPAK 

STOCKPAK is designed exclusively for TRS-80 
users with 32K business systems with two mini-disk 
drives. You can obtain the basic software and sample 
Data Base, plus a comprehensive User's Manual from 
your local Radio Shack Store for only $49.95. The 
STOCKPAK Monthly Data Updating Service can be 
ordered directly from Standard & Poor's for $200 an- 
nually, or from the order form provided in the basic 
package you purchase from Radio Shack. 



s/i 



Standard & Poor's Corporation 

25 BROADWAY, NEW YORK, NY 10004 (212) 248-3993/3374 



Circle 391 on inquiry card. 



Listing 1 continued: 

858 S$<A)=A$--A=A+1'N*N+1-G0T0 828 

•SOURCE DUMP L LXX , LXX-XX 

IF LEN(A$>=1 h=0\B=N-1 

IF LEN(A$»2 A=UAL( RIGHT$< LEFT$( f)$, 4 .>, 3 > > > B=A 

IF LEH(A$»3 B=UhL< RIGHT$< A$, 3 >> 

IF B>N 'B-N-l 

IF A>N :ft=H-l 

IF OK THENFORC-ATOB ■■ GOSUB940 'PRINT C;TAB(€)A$* 

RETURN 

FORC=A TOB ■■ PR INT C , S$< C > > NEX T > RE TURN 



868 
870 
880 
890 

960 
910 
920 
EXT 
930 
940 
950 
960 
970 
9S0 
990 
1 000 

1010 

1020 
1030 
1040 
1050 
1 06O 
1070 
10S0 
1 090 
1 1 OO 
1110 
1120 
1 1 30 
1140 



OBi 



TtiB<22)S$(C):N 



Y=AD< C > •• H= I N T( )■■■■■ 2 56 > « G0SUB9 70 

r-< X*256 > >sl 6 .> > GO SUB 970 
Y-( INK Y---'l 6 >tl 6 ) ) 
THEN A$-A$+CHR$(X+55> ELSE A$*A$+R1GHT$< STR$(M 



i$(C>"S$<C+l>'NEXT 



X=INT< 
X=INT( 
IF X>9 
RETURN 

OK-0 : L C=0 ■ AC=0 ' SOURCE DEL E TE DHH 
B=VAL<RIGHT$<A$* LEN(A$>-1 >> 
IF B>N RETURN 
FOR C=B TO N-l 
N=N-1 i RETURN 

'SYMBOL PRINT 

IF OK THEN 1060 

FOR A-0 TO LC-1 

NEXT: RETURN 

' FILE I/O SUBCMS 1=L0AD S=SAUE 

INPUT "SUBCOMMAND L=LOAD S=SAUE 

IF < B$< > "S " >$( B$< > "L " > THENRETURN 

INPUT " FILE SPEC'S " .; A$ 

IF B$="S" THEN 1170 

OPEN " I"..l , A$ •• INPUT#1 , OK, N 

FOR h=0 TON- 1 ■■ I NPU T# 1 , S$( A .> , 0B$( A > , AD< A > ■■ NEX T 



ELSE RETURN 
< C=LM A > •• GOSUB 



940 : PRINT LA$CA. 



■B$ 



MA. 



:R$: 



Listing 1 continued on page 240 



At last, a full S-100 system 

has been put together on a 

single board with the 

introduction of the Super 

Net/I and the Super Net/ll . 

the space and money 

savers. The Super Net/I 

has eliminated the need 

for four boards in 

existing S-100 

systems. 

Additionally, 

Super Net/I and 

Super Net/ll run 

with cp/m;', 

MP/M" and 

CP/Net \ A most 

revolutionary 

innovafion for all 

OEMs, distributors, 

and system 

houses. 



At Last... 
The S-100 
Revolution 



& ADVANCED 
MICRO DIGITAL 

CORPORATION/, 




FEATURES: 

• S-100 IEEE 

64K of bank select memory 

(16K banks) 

- Z-80 CPU at 4 MHZ (no wait) 

• Floppy disk controller for 

8-inch or 5 Vi-inch drives 

• Two serial (RS-232C) 

and two parallel I/O ports 

Asynchronous (Super Net/I) 

or synchronous (Super Net/ll) 

operations ... A feature that is 

used in network systems 

"i One year warranty (includes 

parts and labor) 

For further information call or write: 

ADVANCED 

MICRO DIGITAL 

CORPORATION 

7201 Garden Grove Blvd., 

Suite E, 

Garden Grove, CA 92641 

(714) 891-4004 

Telex: 678-401 TAB IRIN 



238 December 1981 © BYTE PublicaBons Inc 



Circle 9 on inquiry card. 



Circle 448 on inquiry card. 



isting 1 continued: 

150 CLOSE: RETURN 

169 PRINT "THERE IS NO SOURCE" ■ RETURN 

170 IF N=@ THEN 1160 ELSE OPEN "0" , 1 , A$ • PRINT#1 , OK. 
ISO FOR A-8 TO N-l :PRINT#l..CHR$<34>.;S$<fH>.;CHR$<34>. 
h)j :NEXT 

i 90 B$= " " < CL OSE ■• RE TURN 

200 'COMMAND CONTROL 

210 LINEINPUT"REhDY1: "jA$ ■■ B$=LEFT$(A$, 1 ) 



Ni 

CHR$( 34 . 



0B$( A X; CHR$< 34 .)'; AD 



220 
230 
240 
250 
260 
270 
2S0 
290 
300 
310 
320 
330 
340 
350 
360 
370 
3S0 
390 



B$="L" 
B$="I" 
B$="D" 
B$="R" 

£;$- "Q" 
B$="F" 

B$="S" 
B$="H" 
GOTO 1200 
'IMPLIED 
DATA ABA 



IF 

IF 
IF 
IF 
IF 
IF 
IF 
IF 



GOSUB S60 
GOSUB 760 
GOSUB 990 
THEN 130 



GOSUB 
GOSUB 
GOSUB 
GOSUB 



240 

1 080 
1040 

1550 



DATA DEC A 

DATA PULh 

DATA ASLA 

DATA SBR 

DATA DEX 

DATA NOP 

DATA DAR 
6 .■ TPA 07 
400 DATA LSRA 

DATA END 

'OTHER OPERANDS 



OPERANDS 
1B..CLRA 
4 A.. DECS 
32..FULB 
48..ASLB 
10.. TAB 
09s DES 
02,RTI 
19..CLC 



4F 
5A 



16 
34 
3B 



CLRB 
INCA 
ROLA 
ASRR 
TBA 
INK O 
RTS 
0CCLI 



5F., COMA 43.. COMB 
4C INCB 5C PSHA 
49., ROLB 59..R0RA 
47..ASRB 57 
17.. TSTR 4D.. TSTS 5D 
8.. INS 31.. TKS 35.. 
39.. SHI 3F..HAI 3E 
DE..CLU OAsSEC 



36..PSHB 37 
46..R0RB 56 



TS 



0D.< SET 



UF.. SEU 



OB.. TAP 



44..LSRB 54 



410 
420 
430 
440 



IMHED, DIRECT, INDEX, EXTENT 



450 
460 
470 
4S0 
490 

500 

510 
520 
530 
540 



DATA ADDA 8B9BABBB.. ADDS CBDBEBFB, ADC A 
DATA ANDA S494R4B4, RNDB C4D4E4F4.. BITA 
DATA CLR 6F7F..INC 6C7C, DEC- 
DATA CM PA 8191A1B1..CMPB C1D1E1F1 , EORA 
DATA LDAA 8696A6B6., LDAB C6D6E6F6, OR A A 
DATA SUB A 8D90A0B0, SUBB CDDOEOFO.. SBCA 
DATA TST 6D7D..JMP 6E7E..JSR 
DATA CPX 8C9CACBCLDX CEDEEEFE.. LDS- 
DATA STX DFEFFF..STS 9FAFBF.. 
DATA STAA 97A7B7..STAB D7E7F7 
DATA END 



8999A9E:9.- 
S595A5S5, 

6A7A 
889S'A8B8j 
8A9AAABA, 
8292A2B2, 

ADBD, 
8E9EAEBE 



ADCB 
BITS 

EORB 
ORAB 
SBCS 



C9D9E9F9 
C5D5E5F5 

CSDSE8F8 
CABAEAFA 
C2D2E2F2 



' BRANCH INS TRUCTIONS 

DA TA BRA20 , BCC24 , BCS25.. BE9.2 
6.. BUC28.. BFL2A.. BSR8D.. BUS29 
550 'OPERATING INSTRUCTIONS 
560 CLS:pRINTTAB<20>"**t MINI 
N PAGE FILE 

570 PRINT" INSERT 

PR I NT "DELETE 

PRINT"LIST 

PR I NT "COMPILE 

FRINT"* MOST 



BNE 



BGE2C BGT2E.. BHI22, BLE2F.. BLS23.. BL T2D, SMI1 
6S00 COMPILER *#*"» PR INT "HELP H THIS INSTRUCTI 



5S0 
590 

600 

610 
620 
630 
F,4fi 
650 
660 
670 
680 
690 

700 

710 
720 
730 



SAUE.--LOAD" 
I < ADD TO EXISTING 
DXX ( LINE NUMBER) 
L (ALL TEXT IN BUFFER) 
C SYMBOL PRINT S 

OF THE INSTRUCTION SET I 



TEXT) I XX (ADD BEFORE LINE#)" 
RESTART.--CLEAR R" 
LXX (LINE #) LXXX-XXX (RANGE) 



INCLUDED 
#1A )" 
$1A )" 
X..1A )' 



PRINT" IMMED ADDRESSING #XX ( ADDA 

PR INT "DIRECT ADDRESSING $XX ( ADDA 

PR I NT "INDEXED ADDRESSING X;XX ( ADDA 

FR I NT "EXTENDED ADDRESSING $XXXX ( 

PRINT"IMPLIED NO OPERAND 

PR I NT "OTHER ( ORG XXXX ) LITERALS ($XX HEX) 

PRINT"* SOURCE IS POSTIONAL ENTER AS FOLLOUS 



ADDA $XXXX . 



t 



PRINT "LABEL(<4CH 

'ABEND PROCESSING 

ON ERROR GOTO 1720 'RETURN 

PRINT "ERROR IN "..ERL,"HAS 

RESUME 1200 



$TAB* OPERATION 



$TAB$ 



:x& ascii. 



OPERAND " 



(ERRs2)+l 



240 December 1981 © BYTE Publications Inc 



Give your system 
some NEC, and watch 
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NEC's crisp, clear, high-performance JCI202 NEC's classic green monitor, (JBI20I), one of 
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I 

H 
B 

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M» Pntfott (?) / M& Jf*' 




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WL ■ ■• -■■■-■j 



tten Fr?ss PEftfN, 



Vw entry tl I llq start at the fcesinnin? type I), 



1. How TEflCH K0SK5 J 

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For more information and the name of a dealer near you, please write, call, 
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Designer Software and Polonl.r 



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Circle 122 on inquiry card. 





$$$ MINI 68SQ COMPILER £&$ 


HELP H 


THIS INSTRUCTION PAGE FILE F ShVE--"lO 


7 kj Q C pi 


I ( ADD TO EXISTING TEXT) I XX (ADD BEFORE 


HP' r7r 


'■•■, '•■' '' ' INF NNNSFR ? RES' ThR T-' 'i 'L Eh R R 


L 1 £> i 


/ (ALL TEX!T IN B'N.FFER -' '■ XX -L ?NE $ ) LNX~XX 


COMPILE 


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.WED ;-:? 


DRESSING #XX < ADDA #i« .> 


DIRE CI h 


JUktSoiNb $XX '■ huUh $1h > 


INDEXED 


ADDRESSING X>XX C ADDA X/lft ) 


EXTENDED 


ADDRESSING $XXXX ( ADDA $XXXX) 


IMPLIED 


NO OPERAND 


THER ( 


ORG XXXX) Literals >:$XX HEM) (&XX& ASCII) 


$ SOURCE 


IS POSTIONAL ENTER AS FOLLOMS t 


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UHU 



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KH! 



Figure 1: A help screen with all the commands needed to make the program usable. 

where aaaa is an ASCII string of up to 30 characters. The 
only pseudo-op implemented is the ability to force the 



Text continued from page 229: 

The rest of the commands deal with the 6800 source data. 
As you enter the source code, a line counter is in- 
cremented. All references are based on these line 
numbers: 



L List on the screen all the source text. If it has 

been assembled, the object is also displayed. 

Lxx Display a single line. 

Lxx — yy Display a range of lines. 

Dxx Delete a single line. The source is renumbered. 

lxx Insert before line xx. This is a multiple insert 

that can be terminated by pressing ENTER on 
an empty line. 

I Insert at the end of the source code. Again, this 

is a multiple insert that is terminated by press- 
ing ENTER on an empty line. 

I have taken some liberties in designing my coding con- 
ventions. To be consistent, they are also displayed on the 
HELP screen. First, the operands are a single string. For 
example, use STAA, not STA A, to store accumulator A. 
This concatenated operation code and operand works for 
all instructions. It helps to find the correct op code 
quicker in the tables as I've created them. Literals are 
created as $xxxx for 2 bytes of hexadecimal and &««««&, 



assembly to specific addresses with ORG xxxx, where xx- 
xx is the address in hexadecimal where the assembly is to 
originate. Any number of ORG statements can be used in 
a single program. 

Source input is done in the insert mode. Once in this 
mode, the TAB key plays an important role. An input 
line consists of up to three fields separated by tabs: label 
(4 or fewer characters), operation, and operand; no com- 
ments are allowed in these lines. Comments are entered 
by typing an asterisk in position one. 

Figure 2 shows a sample session with the cross- 
assembler. I loaded a preassembled 6800 program called 
ECHO/M68 from disk. Then I listed all of it. From left to 
right, the contents are: line number, hexadecimal load 
address, assembled object code, label, operation, and 
operand. I assembled and then displayed the symbol 
table. Note that the source and object code are 
automatically saved on disk for use with the download 
function. The S command lists the statement number and 
hexadecimal address of each label requiring address 
resolution. Next, I used the I command to enter a new 
line at the end of the current source program. The line 
numbers are generated by the program. I pressed ENTER 

Text continued on page 250 



GAME DESIGNERS 



CINEMATRONICS, a leader in the coin -operated video game industry, is expanding its game design staff. We are seeking 
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CINEMATRONICS offers competitive salaries, paid sick and vacation time, medical coverage, pension and profit sharing. 

If you're looking for an excellent opportunity with a rapidly growing, employee conscious company, please forward your 
resume to Sandra Baca, Director of Personnel: 

CINEMATRONICS, INC. 

1841 Friendship Drive, El Cajon, CA 92020 

An Equal Opportunity Employer 



242 December 1981 © BYTE Publications Inc 



Circle 61 on inquiry card. 



Cromemco 

introduces 

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In the crowded and confusing marketplace of 
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SUBCOMMAND L-LOAD S- : SftUE ? L 
~ILE SPEC'S ? ECHQs!168 
READY* L 

'SSEMBL 



6 


096 




t DEM 


PR OCR ft 


M FOR TRS-80 CROS. 


1 













-• 


096 




$*** ■ 


SIMPLE E 




3 


003 




$ 1ST 


TIME D RINT OIRCTIONS 


4 


666 


FE6027 


MR IT 


LDX 


CRLF 


5 


003 


BOE07E 




JSR 


$E97E 


§ 


006 


FE882D 




LDX 


ftTXT 


7 


009 


BDE07E 




JSR 


$E07E 


8 


09 C 


FE0027 




LDX 


CRLF 





00F 


SDE07E 




JSR 


$E07E 


10 


012 


FE002D 




LDX 


ftTXT 


1 1 


01S 




* REftO INPUT 


FOR ECHO 


12 


915 


BDE1AC 


REftD 


JSR 


$ElftC 


13 


01 S 


S19D 




CMPft 


#00 


14 


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2395 




BLS 


END 


15 


91C 


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STftft 


X, 00 


16 


01E 


03 




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1? 


01 F 


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END 


LOftft 


#04 


19 


023 


ft 7 00 




S Tftft 


>;'.. OO 


20 


025 


2009 




BRft 


MR IT 


21 


929 




$ LIT. 


ERftL FOR 


' LINE FEED ft HO CR 


*3 


927 


0029 


CRLF 


$0,029 




'■-' "7 


029 


000ft 




$6 00 ft 




24 


02B 


0094 




$0004 




25 


020 


002F 


ft TXT 


$002F 




26 


64ft 




$TEXT 


BUFFER 




O "7 


92F 


45434S4F1 


>656524F4 7524 1 402654595045204 1 4E 



&ECHO PROGRAM TYPE AND ENTER& 
04ft 64 $04 



REftD) 


'.£ 


c 




REftD) 


''$' 


s 




MR IT 




4 


999 


READ 




12 


915 


END 




IS 


921 


CRLF 




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927 


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25 


620 


REftD) 


'$ 


T 





29* ADDED TO END OF PROGRAM 

39 

READY* L 

6 $ DEMO PROGRAM FOR TRS-80 CROSS ASSEMBLER 

1 $ 

2 $$$$ SIMPLE ECHO FROGRftM tttt 

3 £ 1ST TIME PRINT OIRCTIONS 

4 MR IT LDX CRLF 

5 JSR $E07E 

6 LDX ftTXT 

7 JSR $E07E 

8 LDX CRLF 

Figure 2: Sample session with the 6800 cross-assembler program. Figure 2 continued on page 246 

244 December 1981 © BYTE Publications Inc 



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'Apple is a registered trademark of Apple Computer Inc. Cat is a trademark of Novation, Inc. which does not make Apple computers 
"Suggested retail price ***BSR is a trademark of BSR Corporation 

Circle 308 on inquiry card. 



BYTE December 1981 245 



Figure 2 continued: 



1 a 



5 

■0 



?4 





JSR 


$E07E 








j_DN 


hTNT 






t REfi 


INPUT 


FOR ECHO 






READ 


JSR 

CMPA 

SLS 

ST A A 

INN 

BRA 


$E1AC 

#00 

END 
.'■•;'.., 60 

REfiD 






END 


LB A A 
STAA 

BRh 


#04 
H, 06 






4: LI TERAL FO 


? LINE FEED AND 


CR 




crlf 


$0029 

$090H 

$0004 








i'Ji T ';•:' T 


$66£F 








tTEHT 


Qj iPC'C'^' 










&ECHO 


PROGRAM TYPE AND 


£K 


: ER 



READY* D23 



■t ADDED TO END 0: 



WLRhiM 



28 

REhDY* 

Break in 1220 

READY 



■ECHO PROGRAM 
W4 



'Pt tiNL 



^T\ \rV-| 




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246 December 1981 © BYTE Publications Inc 



Circle 161 on inquiry card. 



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the small systems j ourn al 



248 BYTF December 198] 



We give you one thing othei 

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Text continued from page 242: 

at the end of each line and relisted the source code. The 
object code is not listed since I have modified the source 
code. Finally, I deleted the added line and listed the end 
of the text to see if it was gone. 

The cross-assembler I developed is not instantaneous, 
but it really outshines my hand-assembly abilities. It 
doesn't have full checking or diagnostic capability 
because of the added time it would take to assemble using 
BASIC. It does, however, offer a two-pass capability. 
That is, you can use and reference labels that force two 
passes through the source to resolve and build the correct 
object code. Features such as relative branches are also 
available. 

Program Organization 

To help those who might like to modify or enhance the 
editor/cross-assembler program, here is a summary of 
the program's organization: 



420 Handle ORG statements. 

430-450 Select op-code routines. 

470-530 Second pass to resolve addresses. 

540-600 Process implied operands. 

610-710 Process everything except branches. 

720-760 Process branch instructions. 
770-860 Source collection. 
870-990 Source listing. 
1000-1040 Delete command. 
1050-1080 Symbol print. 
1090-1200 File I/O for save/load. 
1210-1310 BASIC command loop. You may add addi- 
tional commands in this section. 
1320-1400 Implied operand table. 
1410-1510 Other op-code table. 
1520-1530 Branch op-code table. 
1540-1680 Help command processing. 
1690-1700 Abend trap. 



140-230 All the array and variable uses are noted in the 

remarks. The key ones are S$ (source), OB$ (object code 

for the source), and AD (assembled address of the 

source). 

250-340 At the first assembly, the op-code dimensions 

are loaded so the first assembly will take a little longer. 

350-760 The main assembly loop. 

370 Handle comments. 

380-400 Handle ASCII literals. 



That's it. You now have a workable TRS-80 cross- 
assembler for the Motorola 6800. 

In part 2, I will complete the package by presenting a 
Z80 I/O linkage program and a BASIC controlling pro- 
gram. When used, you have all the MIKBUG commands 
plus ten breakpoints, a 16-byte hexadecimal display, a 
GOTO address command, and a LOAD of any assem- 
bled program from the TRS-80 disk through MIKBUG to 
the 6800 memory. ■ 



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Circle 392 on inquiry card. 



TM 



Ask BYTE 



Conducted by Steve Ciarcia 



Mystery Card 

Dear Steve, 

I've seen a small circuit 
board for the Radio Shack 
TRS-80 Model I that aug- 
ments the computer's disk 
capabilities. To use it, the 
FD1771 floppy-disk-con- 
troller integrated circuit is 
removed from the computer 
and installed on this mysteri- 
ous card. The card is then 
connected to the empty 1771 
socket via a ribbon cable and 
DIP (dual inline package) 
plug. 

Unfortunately, I don't 
know any more about the 
board, but I'm hoping it will 
let me use 8-inch floppy disks 
on my TRS-80. Can you sup- 
ply more information? 
Raul G Efron 
Rosario, Santa Fe, Argentina 

To my knowledge, the 
only company that makes an 
8-inch floppy-disk-controller 
for the TRS-80 Model I is 
Lobo Drives International. Its 
address is 354 S Fairview 
Ave, Goleta CA 93117, (805) 
683-1576. 

Your mystery board is 
called the Doubler and is 
made by Percom Data Com- 
pany, 211 N Kirby, Garland 
TX 75042, (800) 527-1592; in 
Texas (214) 272-3421. It ac- 
tually is a device that adds a 
double-density FD1791 disk- 
controller chip to the FD1771 
chip in the Tandy Expansion 
Interface. It allows you to 
run either single- or double- 
density drives, which lets you 
store up to four times more 
data on a floppy disk. The 
Doubler board takes the 
place of the 1771, and the 
single-density disk-controller 
chip plugs into the Doubler 
board. To date, it costs about 
$220 in the US and can be 
purchased through autho- 
rized distributors of Percom 
equipment. . . . Steve 



Control Program 
for Microcomputers 

Dear Steve, 

What is CP/M? I try to 
keep up on current tech- 
nology, but this buzzword 
has got me. Has BYTE ever 
reviewed CP/M7 If so, please 
tell me when so I can in- 
vestigate. 
Stephen Gentry 
Evansville IN 

CP/M (Control Program 
for Microcomputers) is an 
operating system originally 
designed to run on Intel's 
8080 microprocessor (it also 
runs on Intel's 8085 and 
Zilog's 7,80). It was written 
and is supported by Digital 
Research, POB 579, Pacific 
Grove CA 93950, (408) 
649-3896. 

CP/M uses the IBM 3740 
"soft-sector" floppy-disk for- 
mat and, usually, 8-inch disk 
drives. Many types of pro- 
grams are supported on 
CP/M, including compilers 
and interpreters for languages 
such as BASIC and FOR- 
TRAN. Also, WordStar and 
Magic Wand (two word pro- 
cessors) and many other 
high-level pieces of software 
are available for the small- 
business-oriented user. 

A comprehensive series of 
articles on CP/M's structure 
and format was written by 
Jake Epstein in S-100 Micro- 
systems magazine (a bi- 
monthly publication of Cre- 
ative Computing, 39 E 
Hanover Ave, Morris Plains 
NJ 07950). This magazine is 
dedicated to S-100 systems, 
and the predominant operat- 
ing system among S-100 users 
is CP/M. 

If after you've learned a lit- 
tle bit more about CP/M you 
want to have a list of its 
features, I recommend that 
you get the CP/M Summary 
Guide, by Bruce Brigham. It 



can be ordered through Ro- 
setta Stone, POB 35, East 
Glastonbury CT 06025. It 
costs $7.95 postpaid in the 
US. . . . Steve 



Lining Up Problems 

Dear Steve, 

Our store purchased a 
TRS-80 Model II. Our future 
plans call for a remote ter- 
minal located about 50 feet 
away from the computer. We 
are wondering what prob- 
lems we may have with such 
a line and what precaution- 
ary steps might be taken. 
Should we use the RS-232C 
port on the Model II, or is 
there a better way to connect 
a remote terminal? 
Lonnie Hartzell 
Dixon IL 

The RS-232C standard is 
specified to operate between 
50 and 9600 bps (bits per sec- 
ond) for up to 50 feet, so you 
should not have any prob- 
lem. If you are running at 
lower data rates (perhaps 
1200 bps), you can separate 
the computer and the peri- 
pheral by as much as 500 feet 
and expect perfectly reliable 
operation. (At least that has 
been my experience.) Unless 
the cable is wrapped around 
an arc welder, you should 
have no problems at all. . . . 
Steve 



Upgrading Kits 

Dear Steve, 

I would like to increase my 
TRS-80's memory capacity 
without spending any more 
money than necessary, and I 
don't want to blow it up in 
the process. 

I have a Model III with 
16 K bytes of memory, which 



isn't enough for some of my 
programming applications. It 
also limits the length of my 
Scripsit documents. I would 
like to add the maximum 
memory the Model III can 
hold (48 K bytes). Radio 
Shack sells 16 K-byte mem- 
ory kits for $119 plus installa- 
tion, while various mail- 
order suppliers advertising in 
BYTE list similar upgrade kits 
for around $29. 

What is the difference be- 
tween these memory upgrade 
kits? Is the installation dif- 
ficult or within the capabili- 
ties of someone who is not a 
computer technician — like 
me7 

Ralph W Karcher Jr 
Broadalbin NY 

Theoretically, any 4116- 
type memory rated for 200 ns 
access time should work in 
your TRS-80 Model III. If 
you carefully disassemble 
your Model III, you should 
be able to add them yourself. 
The sockets are already pro- 
vided, and no jumpers are re- 
quired. 

While quality varies in 
some of the lower-priced up- 
grade kits, the prices of prime 
memory components have 
been dropping so fast that 
you can find many good 
values. Before you place an 
order make sure that the 
chips are guaranteed for 
200 ns operation and that the 
supplier will not substitute 
any other speed. . . . Steve 



D/A Converters 

Dear Steve, 

I'm currently in the process 
of writing music/sound gen- 
eration routines for my Apple 
II Plus. I need a D/A (digital- 
to-analog) converter to put 
into one of the expansion 
slots. Do you know of a sim- 



December 1981 © BYTE Publications Inc 253 



Ask BYTE. 



APPLE n 
PARALLEL { 
PORT 




10K 



/77 



o 

AMPLIFIER 
AUXILIARY 
i 0.05/xF INPUT 



x*> 



10K 



10K 



10 K 



10 K 



10 K 



10K 



Figure 1 




pie, low-cost (under $30) 
design? I have considered us- 
ing various D/A integrated 
circuits, but a simple buffered 
resistor ladder would suffice. 
(The output will eventually 
go through my stereo ampli- 
fier.) 

David R Tribble 
Arlington TX 

You can build a D/A con- 
verter (DAC) for about a 
half-dollar if you can live 
with some minor inac- 
curacies. Since you are plan- 
ning on using a stereo 
amplifier, a DAC designed 
for relative (rather than ab- 
solute) accuracy should be 
fine. 

It doesn't require very 
much to design a DAC: a few 
resistors and an 8-bit latch. 
First, you need to purchase or 
build a parallel port for your 
Apple II. Then, take the 8 
output bits and run them 
through an R/2R resistor lad- 
der as shown in figure 1. 

The DAC in the figure is 
suitable for music and 
speech-synthesis applica- 
tions, but it isn't exactly 
"laboratory grade. " This par- 
ticular type of inexpensive 
DAC is used in the popular 
Orchestra-80 music syn- 
thesizer for the TRS-80 
(manufactured by the Soft- 
ware Affair, Suite 1, 473 
Sapena Court, Santa Clara 
CA 95051). My January 1982 
"Circuit Cellar" will cover 
more accurate D/A con- 
verters. . . . Steve 



Missing Relays 

Dear Steve, 

In your article "Comput- 
erize a Home," you presented 
three possible techniques for 
interfacing a BSR X-10 home 
controller to a computer. 
(See the January 1980 BYTE, 
page 28.) I'm using a Radio 
Shack Plug T«I Power, which 
cannot receive ultrasonic 
signals, although I would 
have preferred a method that 
could. You indicated in the 



article that relays could be 
used to bundle the — 20-volt 
control signals, instead of the 
keyboard, but it is unclear to 
me just exactly how this is 
done. 

William } Penna 
Fort Wayne IN 

The relays can be attached 
to the X-10 unit in two ways. 
One would be to directly sim- 
ulate the operation of CMOS 
(complementary metal-oxide 
semiconductor) multiplexers 
in a matrix pattern where 
you would close the appro- 
priate relay in place of press- 
ing a switch. If you look 
closely at a diagram of the 
unit, you can see that about 
half the relays could be 
eliminated by directly closing 
a particular relay to short the 
two appropriate pins togeth- 
er. If you don't want to have 
16 separate receivers, but 
perhaps only eight, you 
could use fewer relays still. 

As you mentioned, the 
Radio Shack Plug 'N Power 
does not have an ultrasonic 
receiver. I wrote an article for 
Radio Electronics magazine 
in September 1980 that gave 
complete schematics of both 
the command console and 
various receivers. The differ- 
ence between the Radio 
Shack unit and the Sears con- 
troller is that Sears' machine 
contains the circuitry for 
ultrasonic input. This can be 
added to the Radio Shack 
unit, or you can create the 
coded signal (as I did in my 
BYTE article). 

To do this, you would put 
the coded signal through an 
optoisolator and inject it 
directly into pin 7 of the 
28-pin integrated circuit in 
the command console. In ef- 
fect, this would be equivalent 
to receiving signals via the 
ultrasonic link. The unit will 
then function similar to the 
Sears controller. 

OSI (Ohio Scientific) uses a 
similar method in its system 
that incorporates the BSR 
controller. Be careful to make 
sure that you optically isolate 



254 December 1981 © BYTE Publications Inc 



Circle 179 on inquiry card. 



Circle 183 on inquiry card. 



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Ask BYTE. 



the command console from 
the computer, even though 
you are running it on 5 V. 
The command console has no 
isolation transformer and is 
floating at 115 V. The opto- 
isolator will provide you with 
the proper level shift to run 
on the —20 V supply within 
the command console. Also, 
Radio Shack now makes a 
$39 computer-to-AC line BSR 
X-10 transmitter. . . . Steve 



More on Burn-Outs 

Dear Steve, 

I have some additional in- 
formation on the BSR mod- 
ule "burn-out" problem dis- 
cussed in "Ask BYTE" (see 
the April 1981 BYTE, page 
330). 

First, it is important to 
identify whether it is an ap- 
pliance module or a lamp 
module that is burning out. A 
short across an appliance 



module will more likely burn 
out the house fuse than the 
module. Because of this, the 
appliance module should be 
used in high-exposure areas 
like outdoor lights. There is a 
fuse in the appliance module, 
but its job is to protect the 
line and sensor circuit from 
each other and is, in my opin- 
ion, very unlikely to blow. 

The fuse in the lamp mod- 
ule is in the line that feeds the 
load that the module is con- 
trolling. As such, it tends to 
burn out before the module's 
triac in the situation you were 
discussing. This has been my 
experience. I returned two 
lamp modules before I got 
frustrated and took one apart 
to find the fuse. I compared a 
burnt-out module with a 
good one, and I found the 
fuse. It's a sub-hair-sized 
piece of wire that vaporizes 
with no trace when it blows. I 
replaced this with a single 
strand of copper wire from 



zip cord (a single strand from 
the bundle that makes up one 
of the conductors). I think 
this is too big, but it works. 
I'll have to wait and see if the 
triac burns out the next time 
the lamp falls over and blows 
out the bulb. I don't think it 
will. 

Another point not men- 
tioned in your article is that 
BSR will repair the fuse for a 
flat $4 if you ship the dam- 
aged module to the company. 
A high price to replace a fuse, 
but much cheaper than buy- 
ing a new module. 

One other point: I had er- 



ratic operation of some mod- 
ules from certain control 
units at various times of the 
day until I installed a 0.1 /tF 
capacitor across the 220 V 
house feed. This completely 
solved the erratic operation 
and also totally eliminated 
outside interference from CB 
radios, etc. (BSR suggested 
this, and it works extremely 
well.) 

T Gerald Dyar 
West Hartford CT 



Thanks for the informa- 
tion. . . . SteveB 



In "Ask BYTE," Steve Garcia answers questions on any area of 
microcomputing. The most representative questions received 
each month will be answered and published. Do you have a nag- 
ging problem? Send your inquiry to: 

Ask BYTE 

c/o Steve Ciarcia 

POB 582 

Glastonbury CT 06033 
If you are a subscriber to The Source, send your questions by 
electronic mail or chat with Steve |TCE3I7) directly. Due to the 
high volume of inquiries, personal replies cannot be given. Be 
sure to include "Ask BYTE" in the address. 



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What Makes 
Computer Games Fun? 



Rumor has it that when the Space 
Invaders game was first introduced in 
Japan the Japanese treasury ran out 
of the coin that was used to operate 
the game. True or not, the phenom- 
enal popularity of various computer 
games is obvious to anyone who has 
wandered through a shopping mall, 
an airport lounge, or a toy store in 
the last few years. 

Why are these games so captivat- 
ing? And how can the same things 
that make computer games captivat- 
ing be used to make learning with 
computers more interesting and en- 
joyable? To help answer these ques- 
tions, I systematically studied more 
than 100 people playing computer 
games, looking primarily at what 
made the games fun. Then I devel- 
oped a set of guidelines for designing 
highly motivating educational com- 
puter programs. 

Though I focused on making 
educational activities more fun, these 
guidelines can also be used in design- 



Acknowledgments 

This article is based on the author's PhD 
dissertation submitted to the Stanford Univer- 
sity Department of Psychology. Parts of the ar- 
ticle were previously included in the pro- 
ceedings of the Association for Computing 
Machinery Symposium on Small and Personal 
Computer Systems (Palo Alto, California, 
September 19, 1980) and in references 3 and 4. 



Thomas W Malone 

Cognitive and Instructional Sciences Group 

Xerox Palo Alto Research Center 

3333 Coyote Hill Road 

Palo Alto CA 94304 

ing noneducational computer games 
or in making other computer pro- 
grams more fun to use. All of the 
work I discuss in this article is 
described in more detail elsewhere 
(references 3 and 4). 

Survey of Preferences 

As a first step toward finding what 
makes computer games fun, I inter- 
viewed 65 students — from kinder- 
garten through eighth grade — about 
their computer-game preferences. All 
the children had been playing with 
computer games in a weekly class for 
at least two months and some for 
more than two years. The computer 
class teachers provided a list of the 25 
games they judged most popular 
among the students. Then I asked 
each child to rate how well he or she 
liked each game, on a three-point 
scale. 

Table 1 lists all the games in order 
of their average rating by children 
who had played them. One of the 
most interesting questions we can ask 
about these results is what features 
the popular games share that are 
missing in the unpopular games. To 
answer this I rated each game using a 
number of criteria that seemed likely 
to affect their motivational value. 
Table 2 shows the correlations be- 
tween these game features and the 
average ratings the games received 



from the children. 

The most important factor deter- 
mining popularity in this sample was 
whether or not the game had a goal. 
For example, the top three games all 
had obvious goals (getting a high 
score in Petball, trapping the other 
person's snake in Snake2, and de- 
stroying all the bricks in Breakout), 
while the bottom two games had no 
clear goals (conversing with a simu- 
lated psychiatrist in Eliza or filling in 
blanks in a story in Gold). Scoring, 
audio effects, and randomness also 
had high correlations with game 
popularity. The children liked graph- 
ic games and significantly disliked 
word games. 

Even though these results are inter- 
esting, it is impossible to draw strong 
conclusions from this kind of correla- 
tional study. Among other things, the 
results depend entirely on the sample 
of games I used. The other two 
studies I describe focus on a single 
game and systematically vary its fea- 
tures in a series of slightly different 
versions of the game; this allows us to 
make some stronger conclusions. 

Breakout — The first game I studied 
in detail was Breakout. Figure 1 
shows a typical screen display in the 
original Breakout game. The player 
uses a knob to control the position of 
the paddle on the left side of the 



258 December 1981 © BYTE Publications Inc 




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Average 
Game Rating 


Description 


Petball 2.8 


Simulated pinball with sound 


Snake2 2.6 


Two players control motion and shooting of snakes 


Breakout 2.6 


Player controls paddle to hit ball that breaks through a wall, piece by piece 


Dungeon 2.6 


Player explores a cave, like Dungeons and Dragons 


Chase S 2.6 


Two players chase each other across an obstacle course, with sound effects 


StarTrek 2.5 


Navigate through space and shoot Klingon ships 


Don't Fall 2.5 


Guess words like Hangman but, instead of a person being hung, a person or robot advances to a 

cliff 
Guess who committed a murder by questioning witnesses who may lie 


Panther 2.4 


Mission 2.4 


Bomb submarines without getting your ship sunk 


Chaser 2.4 


Capture a moving square with perpendicular lines 


Chase 2.4 


Like Chase S but without sound 


Horses 2.4 


Bet on horses that race along track 


Sink Ship 2.3 


Bomb a ship from an airplane 


Snake 2.3 


Like Snake2 but snakes can't shoot 


Lemonade 2.3 


Run a lemonade stand: buy supplies, advertise, etc 


Escape 2.2 


Escape from moving robots 


Star Wars 2.2 


Shoot Darth Vader's ship on screen 


Maze Craze 2.2 


Escape from randomly generated maze 


Hangman 2.1 


Guess letters of a word before man is hung 


Adventure 2.0 


Explore cave with dragons, etc 


Draw 2.0 


Make any design on the screen 


Stars 2.0 


Guess a number. Clues given by number of stars 


Snoopy 1 .9 


Shoot Red Baron by subtracting Snoopy's position on number line from Red Baron's position 


Eliza 1.8 


Converse with simulated psychiatrist 


Gold 1 .5 


Fill in blanks in story about Goldilocks 


Table 1: 25 computer games, 
2 = like; 3 = like a lot). 


listed according to preference. Sixty-five students were asked to rate the games (1 = don't like; 





Correlation with 


Feature 


Average Preference 


Goal 


0.65** 


Computer keeps a score 


0.56** 


Audio effects 


0.51** 


Randomness involved in game 


0.48** 


Speed of answers counts 


0.36* 


Visual effects 


0.34 


Competition 


0.31 


Variable difficulty level 


0.17 


Cooperation 


0.02 


Fantasy 


0.06 


Kind of game: 




Graphic game 


0.38* 


Math game 


-0.20 


Word game 


-0.38* 


Statistical significance levels: 




*p<0.05 




**p<0.01 




Table 2: Features influencing game preference 


listed according to importance. 


The 25 games listed in table 1 were analyzed in 


terms of these features, and the 


results were correlated with the game preferences from table 1. 



screen. The paddle is used to bounce 
the ball against the wall of bricks on 
the right side of the screen. Each time 
the ball bounces off the wall, it 
knocks one brick out and adds to the 
score. The ultimate goal of the game 
is to knock out all the bricks. 

My survey and other casual obser- 
vations indicate that this is one of the 
most popular contemporary com- 
puter games. What is the "secret" of 
its success? Many devotees of Break- 
out and similar games mention their 
score — usually their highest one — 
when talking about the game. Is the 
challenge of getting a record-high 
score the principal attraction? Is it the 
visual stimulation of watching the 
bricks break out7 Or is it simply the 
enjoyment of the sensorimotor skill 
involved in putting the paddle in 
front of the ball? There are, of course, 
many other features of Breakout, but 
these three — the score, the breaking 



260 December 1981 © BYTE Publications Inc 



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Copyright © 1981 Westico, Inc. 
WES-40 

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WESTICO 

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Circle 256 on inquiry card. 



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out of the bricks, and the ball bounc- 
ing off the paddle — seem to capture 
the essence of the game. 

To examine which of these three 
features was most important to the 
game's appeal, I constructed six dif- 
ferent versions of the game, varying 
each of the three features in all sensi- 
ble combinations. For example, in 
some versions the ball bounced back 
and forth between the wall and the 
paddle but no bricks ever broke out 
of the wall. In other versions the ball 
never bounced off the paddle; it was 
simply "caught" when the paddle was 
placed in front of it. Also, only half 
of the versions had a score. 

I asked 10 college undergraduates 
to play all the versions and then rate 
how well they liked each one. The 
factor that made the most significant 
difference in their ratings was 
whether or not the bricks were 
broken out. It is unclear from this 
study what aspects of the bricks 
breaking out are most important, but 
the list of features in table 2 suggests a 
number of important possibilities. A 
partially destroyed wall of bricks 
presents a visually compelling goal, 
while acting as a graphic score- 
keeping device which tells how close 
the player is to that goal. It thus pro- 
vides a goal, a visual effect, and scor- 
ing at the same time. In fact, the 
wall's structure suggests many goals 
at different levels: knocking out a 
brick in the third row, destroying the 
first row completely, etc. 

The results also showed that the 
versions without scores or bricks 



breaking out were significantly less 
appealing than the other versions. In 
other words, the versions in which 
there was no clear goal— other than a 
vague "keep the ball going as long as 
you can" — were significantly less fun 
than the others. Without a clear goal, 
it was not really a game at all. 

I believe a similar combination of 
multiple-level goals and visual effects 
is important in the success of a num- 
ber of other games, like Space In- 
vaders, Snake2, and Petball. 

Darts — The second game I studied 
in detail was called Darts, designed to 
teach elementary students about frac- 
tions (see reference 2). In the version I 
used, three balloons appear at ran- 
dom places on a number line on the 
screen and players try to guess their 
positions (see figure 2). They guess by 
typing in mixed numbers (whole 
numbers and/or fractions), and after 
each guess an arrow shoots across the 
screen to the specified position. If the 
guess is right, the arrow pops the bal- 
loon; if wrong, the arrow remains on 
the screen. The player gets to keep 
shooting until all the balloons are 
popped. Circus music is played at the 
beginning of the game; if all three 
balloons in a round are popped in 
four tries or less, a short song is 
played after the round. 

To discover what features contri- 
bute most to the appeal of this game, 
I constructed eight different versions 
of the game by removing, one at a 




SCORE 12 

3 BALLS LEFT 



Figure 1: A typical display from the 
Breakout game, which is popular because 
it provides a clearly defined challenge 
(breaking through the wall by bouncing 
the ball against the bricks) and provides 
visual and auditory stimulation. 



Figure 2: A display from the Darts game, 
a program to teach fractions. The object is 
to break each balloon by typing in the 
mixed number corresponding to the 
balloon's position on the number line. 
This is an example of an intrinsic fantasy 
because the skill with fractions depends 
upon the fantasy of pinpointing the 
balloons on the line and vice versa. 



262 December 1981 © BYTE Publications Inc 



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time, features that were presumably 
motivational. For example, some ver- 
sions of the game had rectangles in- 
stead of balloons marking the place to 
be guessed on the number line and 
short lines instead of arrows marking 
the incorrect guesses. The features I 
removed in this way included the fan- 
tasy of arrows popping balloons, the 
music, the scorekeeping, and several 
different kinds of feedback. 

I assigned 10 different fifth-grade 
students to each of the eight versions 
and then allowed them to play with 
their version of Darts or with a ver- 
sion of Hangman that was the same 
for all students. My primary measure 
of the appeal of different versions was 
how long the students played their 
version of Darts in comparison to 
Hangman. This measure was also 
highly correlated with how well 
students said they liked the game at 
the end. 

Although important in 

creating interesting 

educational programs, 

fantasies must be 

carefully chosen to 

appeal to the target 

audience. 

The results of this experiment 
showed a significant difference be- 
tween what boys and girls liked about 
the game. Judging from time spent on 
various versions of the game, boys 
liked the fantasy of arrows popping 
balloons; girls apparently disliked it. 
I do not think the implication is that 
boys should be given one kind of fan- 
tasy and girls another. Instead, I 
think it would be better to let each 
person choose whichever fantasy 
seems most appealing at the time. 
Still, understanding sex differences 
like this may help avoid uninten- 
tionally designing programs that for 
instance appeal more to boys than 
girls. I think the most significant im- 
plication of this experiment is that, 
although they are important in 
creating interesting educational pro- 
grams, fantasies must be carefully 
chosen to appeal to the target au- 



264 December 1981 © BYTE Publications Inc 



Circle 265 on inquiry card. 





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266 December 1981 © BYTE Publications Inc 



Challenge 

Goal 
D Does the activity have a clear goal? If not, is it easy for the students to determine 

goals of appropriate difficulty for themselves? 
□ Are the goals personally meaningful? 



□ 



D 



Uncertain outcome 

Does the program have a variable difficulty level? 

□ Determined by the student 

□ Determined automatically, depending on the student's skill 

□ Determined by the opponent's skill 
Does the activity have multiple goal levels? 

□ Scorekeeping 

D Speeded responses 
Does the program include randomness? 
Does the program include hidden information selectively revealed? 



Fantasy 

□ Does the program include an emotionally appealing fantasy? 

□ Is the fantasy intrinsically related to the skill learned in the activity? 

□ Does the fantasy provide a useful metaphor? 

Curiosity 

Sensory curiosity: audio and visual effects 

□ as decoration 

□ to enhance fantasy 

□ as a reward 

□ as a representation system 

Cognitive curiosity 

□ Does the program include surprises? 

D Does the program include constructive feedback? 

Table 3: A checklist for designing enjoyable educational programs. 



dience. Otherwise, they may actually 
make the environment less interesting 
than it would have been without 
them. 

Guidelines 

How can we use these results to 
make educational programs more fun 
for students? I think the character- 
istics that make instructional en- 
vironments interesting can fit natural- 
ly into one of three categories: 

• challenge 

• fantasy 

• curiosity 

A checklist of these characteristics is 
shown in table 3. 

Challenge — For an activity to be 
challenging, it should have a goal 
whose outcome is uncertain. In my 
survey, the feature I found most 
highly correlated with game populari- 
ty was the presence of an obvious 
goal. In the Breakout study, students 
rated the versions of the game with 
no obvious goal as significantly less 



enjoyable than those with a clear 
goal. Thus simple games, to be 
challenging, should probably have a 
single fixed goal. More complex en- 
vironments (like graphics editors or 
computer programming languages) 
should be designed so that users can 
easily generate goals of appropriate 
difficulty. For example, in the LOGO 
system (see reference 5), students can 
program a moving "turtle" to draw 
designs on a computer screen or on 
the floor. The attractiveness of this 
environment is the ease with which 
children think of things they would 
like a moving turtle to do. But unless 
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solving arithmetic problems). 

If a person is either certain to reach 
the goal of an environment or certain 



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not to reach it, the environment is un- 
likely to be challenging. There are 
several ways of ensuring that people 
of varying abilities (and the same per- 
son over time) will be challenged by a 
program. The first is simply to have a 
variable difficulty level, which can 
be: 

• determined automatically (as in 
many drill-and-practice programs) 

• chosen by the person (perhaps with 
ego-involving labels like cadet or 
commander) 

• determined by the opponent's skill 
(as in chess and checkers) 

Competition may be motivating sim- 
ply because it provides a challenge at 
an appropriate difficulty level. 

A more subtle way of making the 
outcome uncertain puts multiple goal 
levels in the same environment. For 
example, in the Darts game the first- 
level goal is simply to pop all the 
balloons. But players who are certain 
to reach this goal can still be chal- 
lenged by the goal of popping all the 
balloons in as few tries as possible. 
Many motivating environments, 
from games like chess to activities like 
computer programming, have this 
characteristic: different people in the 
same general environment can pick 
very different goal levels. 

Two features of computer games 
that help provide different goal levels 
are scorekeeping and speeded 
responses. Someone who can already 
reach the basic goal of an environ- 
ment can still be challenged by trying 
to do it faster or better. These 
features are especially useful in in- 
structional situations like drill-and- 
practice where the purpose is to im- 
prove previously learned skills. A 
third way of providing uncertainty is 
through hidden information that is 
selectively revealed (as in Hangman) 
or by randomness (as in all gambling 
games and many simulations). 

Goals and challenges are captivat- 
ing because they engage a person's 
self-esteem. Success in a computer 
game — like success in any challenging 
activity — can make people feel better 
about themselves. The opposite side 
of this principle is, of course, that 
failure in a challenging activity can 



lower a person's self-esteem and, if it 
is severe enough, decrease the 
person's desire to repeat the activity. 
One implication of this principle is 
simply that instructional games 
should have a variable difficulty 
level. Another implication is that per- 
formance feedback should be pre- 
sented in a way that minimizes the 
possibility of damage to one's self- 
esteem. Comments like "You need 
more practice, dummy!" usually have 
no place in an educational environ- 
ment. 

This analysis of challenge il- 
luminates an important distinction 
between toys and tools. Toys can be 
defined as systems used for their own 
sake, with no external goals (com- 
puter games, puzzles, etc). Tools can 
be defined as systems used to achieve 
external goals (text editors; program- 
ming languages, etc). With respect to 
challenge, the requirements for good 
toys and good tools are mostly op- 
posite. Since a good tool is designed 
to achieve goals that are already pre- 
sent in the external task, it does not 
need to provide a goal. Furthermore, 
since the outcome of the external goal 
(such as writing a good letter or get- 
ting a program to work) is already 
uncertain, the tool itself should be 
reliable, efficient, and usually "invisi- 
ble." 

In a sense, a good game is supposed 
to be difficult to play: that increases 
its challenge; but a tool should be as 
easy as possible to use. This distinc- 
tion helps explain why some users of 
complex computer systems may take 
a perverse pleasure in mastering tools 
that are extremely difficult to use. To 
the extent that these users are treating 
the systems as toys rather than tools, 
the difficulty increases the challenge 
and therefore the pleasure of using 
them. 

Fantasy — One relatively easy way 
to increase the fun of learning is to 
take an existing curriculum and over- 
lay it with a game in which the player 
progresses toward some fantasy goal 
(as in Baseball) or avoids some fan- 
tasy catastrophe (as in Hangman), 
depending only on whether the 
player's answers are right or wrong. 
These are examples of extrinsic fan- 



268 December 1981 © BYTE Publications Inc 



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Some Educational Games 

Game Description 

Adventure The player explores a vast underground system of caves 

with dragons, etc, trying to find treasures. The cave is filled 
with knife-throwing dwarves and other dangers. 

Baseball Players advance around a baseball diamond by picking 

correctly spelled words from sets of alternatives. 

Darts (See text) 

Hangman The player tries to guess a word, letter by letter. After 

each incorrect letter guessed, one more body part of a man being 
hung is drawn. The player loses if the whole body is drawn. 

Hammurabi Player acts as king of ancient Babylonia and decides each 
year how much wheat to plant, how much to store, and how 
much to save. There are occasional plagues, rat infestations, etc. 
The number of people who are born, starve, etc each year is 
reported. 

Hurkle The player tries to guess where an animal called a 

"Hurkle" is hiding in a Cartesian coordinate grid. Feedback after 
incorrect guesses tells which direction to move. 

Lemonade The player runs a lemonade stand, buying supplies, 

advertising, etc. There are random fluctuations in weather, 
number of customers, etc. Each day's expenses, sales, and pro- 
fits are computed. 

Snoopy Snoopy and the Red Baron appear at different positions 

on a signed number line. Player says how far Snoopy should 
shoot to hit the Red Baron (as a signed integer). 



Academic Knowledge Used 

reading, writing 



spelling 

number lines, fractions, estimation 
spelling, vocabulary 



elementary economics 



Cartesian coordinates, map directions 



elementary economics 



subtraction, number lines, negative 
numbers 



Extrinsic fantasies in which a fantasy goal is approached 
A train on a track is approaching a city 

A rocket is passing the other planets of the solar system on its way to earth 
A complicated building is being built, piece by piece 
A fleet of space invaders is being destroyed, one by one 

Extrinsic fantasies in which a fantasy catastrophe is avoided 

A person is hung, one body part at a time 

A person advances toward the edge of a cliff, one step at a time 

A time bomb is ticking toward an explosion 

Table 4: Samples of extrinsic fantasies that could be used to add enjoyment to many 
educational programs. (Extrinsic fantasies are those in which the fantasy depends on 
using the skill but not vice versa.) 



tastes, in which the fantasy depends 
on the use of the skill but not vice ver- 
sa. 

Other factors, such as answering 
speed, can also affect intrinsic fan- 
tasies. For example, the Speedway 
game (in which students' race cars 
move along a racetrack depending on 
how fast they answer arithmetic 
problems) is an extrinsic fantasy. 
Since the use of the skill does not de- 
pend on the fantasy, the same fantasy 
could be used with completely dif- 
ferent kinds of problems. For exam- 



ple, Baseball and Hangman fantasies 
could just as well be used for arithme- 
tic problems as for spelling problems: 
players could be "hung" or advanced 
around a baseball diamond depend- 
ing on whether the arithmetic prob- 
lems are worked correctly. Table 4 
lists a few possible extrinsic fantasies. 
Conversely, intrinsic fantasies not 
only depend on the skill, but the skill 
also relies on the fantasy. This usual- 
ly means that problems are presented 
in terms of fantasy-world elements, 
and players receive a natural con- 



structive feedback. For example, in 
Darts the skill of estimating distances 
is applied to the fantasy world of 
balloons on a number line and 
players can see graphically whether 
their answers are too high or too low 
and, if so, by how much. 

Other intrinsic fantasies in math 
games include the search for a hidden 
animal on a Cartesian grid in the 
Hurkle game and Snoopy shooting at 
the Red Baron on a number line in the 
Snoopy game. The Adventure game, 
in which a vast underground cavern 
system is explored in response to the 
player's commands, can be con- 
sidered an intrinsic fantasy for the 
skills of reading (the cave descrip- 
tions) and writing (the commands). 

I think intrinsic fantasies are more 
interesting and instructional than ex- 
trinsic fantasies. One advantage of in- 
trinsic fantasies is that they often in- 
dicate how the skill could be used to 
accomplish some real-world goal (as 
in a business-simulation game like 
Lemonade). More importantly, in- 
trinsic fantasies can provide meta- 



270 December 1981 © BYTE Publications Inc 



Circle 119 on inquiry card. 



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phors or analogies that help a learner 
apply old knowledge in understand- 
ing new things. For example, in the 
Darts game learners are able to use 
their old knowledge about some ob- 
jects being higher or lower than 
others to learn about the relative sizes 
of fractions. Finally, by provoking 
vivid images related to the material 
being learned, intrinsic fantasies may 
help the learner remember the 
material. 

Computer-game fantasies almost 
certainly derive some of their appeal 
from the emotional needs they help 
satisfy. Of course, it is difficult to 
know what emotional needs people 
have and how these needs might be 
partially met by computer games. But 
it is clear that different people find 
different fantasies appealing. If in- 
structional designers can create many 
different fantasies for different peo- 
ple, their activities are likely to have 
much broader appeal. For example, it 
is easy to imagine a math game in 
which different students see the same 
problems but can choose the accom- 
panying fantasy according to in- 
dividual preference. Instructional de- 
signers might also create en- 
vironments into which students can 
project their own fantasies. For in- 
stance, students could name im- 
aginary participants in a computer 
game. 

Curiosity — The final character- 
istic of intrinsically motivating in- 
structional environments is that they 
stimulate and satisfy curiosity. En- 
vironments can evoke a learner's 
curiosity by providing an optimal 
level of informational complexity (see 
references 1 and 6). In other words, 
the environments should be neither 
too complicated nor too simple with 
respect to the learner's existing 
knowledge. They should be novel 
and surprising but not completely in- 
comprehensible. In general, an op- 
timally complex environment will be 
one where the learner knows enough 
to have expectations about what will 
happen, but where these expectations 
are sometimes unmet. 

Sensory curiosity involves the 
attention-attracting value of changes 
in the light, sound, or other sensory 
stimuli of an environment. Colorfully 



illustrated textbooks and tactile 
teaching devices (like those used in 
Montessori schools) take advantage 
of sensory curiosity. Computers pre- 
sent even more possibilities for music, 
animation, and other audio and 
visual effects. These effects can be 
used: 

• as decoration (like the circus music 
at the beginning of Darts) 

• to enhance fantasy 

• as a reward 

• as a representation system that may 
be more effective than words or num- 
bers (like the graphic representations 
of fractions in Darts and the different 
tones used to signal bounces and 
misses of the ball in Breakout). 

An instructional program can also 
provoke curiosity by presenting a 
paradox or revealing an incomplete- 
ness in the learner's existing beliefs. 
To engage learners' curiosity, the 
feedback from a program should 
sometimes be surprising. It should 
also be constructive in helping the 
learners remove the misconceptions 
that caused them to be surprised in- 
itially. 

For example, some Darts game 
players may have the misconception 
that increasing the denominator of a 
fraction increases the fraction. These 
players will be surprised when they 
try to shoot an arrow higher than the 
last one, only to see it go lower. But 
they will then have enough informa- 
tion to correct their misconception. 
Whether they actually do learn from 
this constructive feedback is another 
very interesting question. Designing 
programs that provide usable con- 
structive feedback for many different 
misconceptions is a difficult but im- 
portant task. 

Another way to sustain 
curiosity — and facilitate learning — is 
to provide a sequence of increasingly 
complex tasks. Each one introduces a 
complication that may surprise the 
learner, but all are within the 
learner's ability to grasp. Providing 
this kind of constructive feedback 
and progressive complexity often re- 
quires a very detailed educational 
analysis of the skills being learned. It 
may also require an on-line model of 



272 December 1981 © BYTE Publications Inc 



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BYTE December 1981 



273 



the learner's knowledge so the pro- 
gram can automatically adapt to the 
learner's current abilities. 

Other Factors — In concentrating 
on what computer games can tell us 
about how to design interesting 
educational programs, I have omitted 
two other important ways of making 
learning fun. First, since the main 
way of knowing what people like is 
by what they choose, I have taken 
for granted that self-motivated 
learners have a great deal of choice 
about their own goals. This element 



of being able to choose can itself be 
very important in making learning 
fun, with or without computers. 

Second, I have concentrated on 
features that can be present in all 
learning environments — even those 
with only one person. The involve- 
ment of other people, both coopera- 
tively and competitively, can also be 
an important way of making comput- 
er-based learning more fun. 

Applications 

One use of the checklist in table 3 is 
to suggest additions to existing or 



SORCERER SOFTWARE 



SUPER ASTEROIDS by Apollo 

'A new era in real time graphic arcade 
games'. 

Never has there been such a captivating and superbly written 
arcade game for the Sorcerer. Styled after the well known and 
very popular ASTEROID DELUXE arcade game, SUPER ASTER- 
OIDS is destined to become the most popular piece of demonstra- 
tion software used by dealers and users alike. Perhaps it is the 
outstanding use of fine line graphics or the silky smooth 
movement. Maybe it is the breathtaking speed, dazzling 
explosions, gripping sound effects or simply the challenge of 
avoiding those fire balls from that persistent flying saucer that 
insidiously follows you across the screen. Whatever it is, we 
warn you NOT to purchase this game for fear that you may join 
the ranks of hundreds of other ASTEROID Addicts who, square 
and bleary eyed at 3 am, just MUST have ONE more go at trying 
to beat that High Score. 

The object is to guide a small space ship across the screen 
avoiding but shooting asteroids as they glide past. When an 
asteroid is hit, it will break up into many smaller pieces. By 
repeatedly hitting the pieces they will soon disintegrate and 
disappear. If you crash your ship into an asteroid it will break 
into pieces and splinter across the screen in a shower of sparks! 
However, if you manage to stay in one piece, chances are you'll 
soon be pursued by a flying saucer that shoots balls of fire! Best 
that you treat him with care, else you may make his friends 
VERY aggressive. 

Apollo has used a novel but ingenius method of continually 
reprogramming graphics characters and has obtained stunning 
results! All movement is done pixel by pixel but without speed 
loss. Numbers of asteroids, directions, speeds and such like are 
all totally unpredictable. If you can show us a piece of software 
that has finer, smoother and faster graphics than SUPER ASTER- 
OIDS, we guarantee to refund your money in full! 

Cassette $29.95 

ZAP80 'Secret Code 
Disassembler', by Ian Robinson 

This is far from your average run-of-the-mill disassembler! Other 
than being a mere 4K long, able to disassemble at the speed of 
light and packed with options, ZAP80 will display before your 
very eyes all those unknown instructions ZILOG never talk 
about! Ian has been doing extensive research into the actions of 
the Z80 processor when confronted with the 700 or so undocu- 
mented (and so called 'illegal'} code sequences. Over 100 of 
these are VERY useful! Did you know you have extra 8 bit 
registers and a complete set of instructions to manipulate them? 
Did you know about extra rotate instructions? 

ZAP80 will disassemble ANY code sequence. Nothing is illegal! It 
will allow you to program with codes that no other disassembler 
can decipher! Think about that .... 

ZAP80 comes with documentation and explanation of all new 
mnemonics used. Three versions are supplied that reside in low, 
mid and high memory. Options include ASCII output, screen 
pause and customised printer control. 

Whether you are a serious programmer, a beginner or simply 
curious, ZAP80 is a piece of software you must have. Come and 
play a REAL adventure game! 

Cassette $24.95 



HOW TO ORDER: 

ALL PRICES ARE IN AUSTRALIAN DOLLARS. 

One Australian dollar equals 1.16 American and 1.4 
Canadian. All programs come standard on cassette 
but some may be requested on either Micropolis II 
Quad density or VISTA 5 'A" diskettes for an addi- 
tional cost of $5.00 per diskette. Note that more 
than one program will fit on a diskette. Programs 
available or diskette include CIRCUS, GALAXIANS, 
GROTNIK WARS and ZAP80. 
$2 discount if this form is used. (Photostat will 
suffice). 



PROGRAM 



PRICE 



Postage within Australia is $1 for initial item 
and 50c for each additional. Outside Australia is 
$2 and 50c. 



Less $2 Discount 
TOTAL 



$2.00 



I enclose, 

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amount, or 



(b) My credit card, expiry date 

{Master Charge, Visa, Bankcard, American 
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No 

My name and address: 

NAME: 

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POST THE ABOVE FORM TO: 

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TELEPHONE: ISD (619) STD (09) 339 3842 

Sunday through to Friday. 

Ask for Richard Swannell for personal service. 

We are a dynamic Western Australian enterprise 

whoe sole aim is to bring you the best in Sorcerer 

software. 

A catalogue such as this is produced regularly and 

sent to approximately 2000 interested Sorcerer 

users in all parts of the world. Let us know if you 

wish to be included on our mailing list. 



planned computer games. Almost no 
computer games include all the fea- 
tures just mentioned, and it is usually 
possible to determine ways in which 
any given game could incorporate 
more of them. For example, at least 
one-fifth of the games in table 1 have 
no way of varying the difficulty level 
and could probably be improved by 
adding this. 

Here are more examples of how the 
checklist can be applied in designing 
educational computer programs. 

A Typical Arithmetic Drill-and- 
Practice Program — In most of these 
programs, the difficulty level of 
arithmetic exercises is automatically 
adjusted according to how well the 
student does, and the percent of prob- 
lems correct is printed at the end of 
each lesson. At first glance this 
automatic difficulty-level adjustment 
appears to be a good way of main- 
taining the program's challenge. But 
according to the previously described 
principles, a goal is the first necessary 
element of a challenging environ- 
ment. The only thing resembling a 
goal in this program is the percent 
correct printed at the end of each 
lesson, and some students do try to 
get "hundred percents." But this goal 
is not made particularly obvious or 
compelling, and, given the automatic 
difficulty adjustment, it is fairly rare 
for students to get all their problems 
correct. In fact, since the difficulty 
adjustment is hidden from the 
students, the goal of getting all the 
problems correct may seem inex- 
plicably receding as students ap- 
proach it. 

Aside from major curriculum revi- 
sions involving intrinsic fantasies and 
curiosity-driven learning, 1 think 
there are still a number of ways that 
extrinsic fantasies can be combined 
with goals and performance feedback 
to make this program more interest- 
ing. One simple way is to select an ex- 
trinsic fantasy like those listed in 
table 4 or better yet, let the students 
pick their own fantasies from a list. 

Ideally, this fantasy can be 
represented graphically and will re- 
main on the screen throughout a 
lesson as correct and incorrect 
answers affect a student's progress in 



274 December 1981 © BYTE Publications Inc 



Circle 401 on Inquiry card. 



OTHERS MAY SEE 
THE ERRORS OF YOUR WAYZ 

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the fantasy world. It would be nice to 
use sound effects for right and wrong 
answers. Reaching the final goal or 
catastrophe in the fantasy world 
should be accompanied by more 
elaborate sound and graphics. 

In addition to the first two levels of 
goals within a lesson (getting in- 
dividual right answers and reaching 
the fantasy goal), the automatic dif- 
ficulty adjustment can provide a 
higher-level goal of making progress 
in the curriculum. If the extrinsic fan- 
tasy includes multiple goal levels, the 
student's movement to a higher dif- 



ficulty level can be accompanied by 
even more fanfare in the fantasy 
world. Obviously, the details of these 
changes still have to be worked out. 
But this short description shows how 
the preceding principles can be used 
to suggest changes to existing pro- 
grams. 

A Simple Program to Teach 
Children How to Tell Time — In this 
example I will suggest how to in- 
crease the interest of a proposed com- 
puter system for teaching the rela- 
tionship between three different nota- 



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tional systems for time: clock face, 
digital display, and English words. 
The original proposal for this system 
(from Laura Gould) was to have the 
three different representational sys- 
tems displayed on the screen at the 
same time so that when the student 
changed any one representation, the 
other two also changed. 

One insight from the above 
checklist is that there is no obvious 
goal for students working with this 
program. A goal is nicely provided 
through an analogy with the Darts 
game. In this new game, a time is 
represented in one system — 
say clock face— and the student tries 
to guess the time in one of the other 
systems — say digital display. Each in- 
correct guess is displayed on the clock 
face, just as the incorrect guesses in 
Darts are displayed on the number 
line. This game might be even more 
interesting if it included an intrinsic 
fantasy about setting alarm clocks 
and being early or late for school. 

Other Educational Applications- 
More generally, a game can suggest 
analogous games in subjects very dif- 
ferent from the original one. For ex- 
ample, a guessing-game structure can 
be used to invent games to teach 
many different kinds of knowledge: 

• To teach an ordered list, use a 
guessing game that gives high/low 
feedback. For example, to teach the 
list of US Presidents in order use a 
game in which the players try to guess 
a secret President. After each guess, 
they are told whether their guess is 
before or after the secret President 
and perhaps how close it is. Such a 
game can be used to teach either the 
contents of a list (US Presidents, steps 
in a procedure, etc) or the ordering 
relationship ("less than" and "greater 
than" in a number-guessing game). 

• To teach the correspondence be- 
tween two representation systems, 
use a guessing game that gives hints in 
one system and asks players to guess 
in the other. For example, the Darts 
game is designed to teach the relation- 
ship between numbers represented on 
a number line and in mixed-number 
format. I just described a similar 
game to help teach children how to 



276 December 1981 © BYTE Publications Inc 



tell time. Such a game can also be 
used to teach correspondences like 
foreign language vocabulary, Carte- 
sian coordinates for points on a plane 
(Hurkle), or spelling of words 
(Hangman). 

• To teach the characteristics of items 
in a set, use a guessing game in which 
players try to guess a target item by 
asking questions about its character- 
istics (like "twenty questions"). For 
example, medical students could try 
to guess the disease a simulated pa- 
tient had by asking questions about 
symptoms and laboratory test results. 
Geography students could try to 
guess a target country by asking ques- 
tions about its climate, economy, and 
so on. 

This technique of using structural 
analogies with old games seems to be 
a powerful way of inventing educa- 
tional games in new subject areas. 

Computer Programming — In some 
senses, computer programming is one 
of the best computer games of all. In 
the "computer programming game," 
there are obvious goals and more are 
easily generated. The "player" gets 
frequent performance feedback (feed- 
back that is often tantalizingly mis- 
leading about the nearness of the 
goal). The game can be played at 
many different difficulty levels, and 
many goal levels are available, both 



References 

1. Berlyne, D E. Structure and Direction in 
Thinking. New York: John Wiley & Sons, 
Inc, 1965. 

2. Dugdale, S and D Kibbey. Fractions Cur- 
riculum of the PLATO Elementary School 
Mathematics Project. Urbana Illinois: 
Computer-based Education Research 
Laboratory Technical Report. University of 
Illinois, October 1975. 

3. Malone, T W. What Makes Things Fun to 
Learn? A Study of Intrinsically Motivating 
Computer Games, Technical Report 
Number CIS-7 (SSL-80-11). Palo Alto, 
California: Xerox Palo Alio Research 
Center, 1980. 

4. Malone, T W. "Toward a Theory of Intrin- 
sically Motivating Instruction." Cognitive 
Science (5, number 4, in press), 1981. 

5. Papert, S. Mindstorms: Children, Com- 
puters, and Powerful Ideas. New York: 
Basic Books, 1980. 

6. Piaget, J. Play, Dreams, and Imitation in 
Childhood. New York: Norton, 1951. 



in terms of the finished product 
(whether it works, how fast it works, 
how much space it requires, etc) and 
the process of reaching it (how long it 
takes to program, etc). Self-esteem 
is crucially involved in this game, and 
occasional emotional or fantasy 
aspects are likely involved in con- 
trolling so completely, yet often so in- 
effectively, the behavior of this 
response entity. Finally, the process 
of debugging a program is perhaps 
unmatched in its ability to raise ex- 
pectations about how the program 
will work, only to have the expecta- 



tions surprisingly disappointed. 

Conclusion 

With computer costs decreasing 
dramatically, their spread into homes 
and classrooms appears inevitable. 
But it is not so certain that these new 
educational applications will use the 
unique capabilities of computers to 
make learning more efficient, more 
interesting, and more enjoyable. I 
think the guidelines I have presented 
here can help in creating instructional 
computer programs that fascinate as 
well as educate their users. ■ 



I HAZELTINE1500 $ 885. 

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JOHN D. OWENS 

Associates, Inc. 

SEE OUR AD ON FACING PAGE 



December 1981 © BYTE Publications Inc 277 



System Notes 



The Game of Left/ Right 



Truck Smith 

1520 Fairgreen 

Fullerton CA 92633 



One of the more fascinating states of consciousness a 
person can be in is the trance. There are phrase-based 
trances, contemplation trances, and trances based on not 
thinking at all. There are Hindu, Buddhist, and Christian 
trances. Modern science has added two: the TV trance 
and the TV-game trance. 

I first noticed the TV-game trance when the quality of 
my concentration changed while I was playing a game of 
Pong in a bar. Though still intensely aware of the game, I 
became cognizant of my surroundings — friends talking, 





Score 


Box Position Background 


Bar Colors 


0-2 


centered black only 




3-5 


centered black or grey 




6-8 


centered black or grey 


change at 6 


9-11 


left or right black or grey 




12-14 


left or right left and right* 


change at 12 


15-17 


left or right left and right* 




18-20 


one corner left and right* 


change at 18 


21-23 


one corner corners'*" 




24-26 


one corner corners"*" 


change at 24 


27 + 


one corner corners*" 


change every time 


*Each side of the screen can be either black 


sr grey, independent 


of the other. 




+ Each 


corner of the screen can independently be either black or 


grey. 






Table 1: Program complications. As the 


game of Left/ Right 


progresses, the box position, the background color, and the 


bar co 


lors complicate the game. More cc 


implications can be 


added by changing the shape of the box 


or having it move 


across 


the screen. 





278 December 1981 © BYTE Publications Inc 



the jukebox playing, a discussion at the bar — yet this 
state did not interfere with the game. 

Since then, I have watched other TV-game players and 
observed a similar phenomenon; the best seem to enter a 
trance where they play but don't pay attention to the 
details of the game. 

Unfortunately, the person who studies this 
phenomenon, either in himself or others, will find that 
TV games come in packages difficult to modify. Since the 
game's parameters cannot be changed, the experimenter 
cannot investigate the experience's limitations. 

Here, I present a computer game that invokes the 
trance-like behavior and is easily modified for further 
study. Best of all, the game is fun to play. Written in 
Apple II Integer BASIC, the game should not be too diffi- 
cult to implement on other computers with a minimum of 
equipment. 

The Game 

You sit in front of a color TV set, a push-button switch 
in either hand. On the TV screen is a colored box and two 
colored bars are at the bottom. The bars line the left and 
right sides of the screen. The box and the left bar are the 
same color. You push the button in your left hand and 
score your first point in the game of Left/Right. 

As you play, the background occasionally changes to 
grey. When this happens, you ignore the button for the 
bar whose color matches the box and press the other 
button. The game continues. 

The box begins to appear in different positions on the 

Text continued on page 292 
Tables, figures and listings 
continued on pages 282-290 



w* 








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fjiil 


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1 i J ■ 


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Memory — you never seem to have quite 
enough of it. 

But if you're one of the thousands of Apple 
owners using the SoftCard, there's an economical 
new way to expand your memory dramatically. 

16K OH A PLUG-IN CARD. 

Microsoft's new RAMCard simply 
plugs into your Apple II,"" and adds 16k 
bytes of dependable, buffered 
read/write storage. 

Together with the SoftCard, 
the RAMCard gives you a 56k 
CP/M"" system that's big enough 
to take on all kinds of chores that 
would never fit before (until now, 
the only way to get this much 
memory was to have an Apple 
Language Card installed). 

GREAT SOFTWARE: 
YOURS, OURS, OR THEIRS. 

With the RAMCard and 
SoftCard, you can tackle large- 
scale business and scientific 
computing with our COBOL and 
FORTRAN languages. Or greatly 
increase the capability of CP/M 




B 






applications like the Peachtree Software account- 
ing systems. VisiCalc™ and other Apple software 
packages can take advantage of RAMCard too. 

And RAMCard gives you the extra capacity to 
develop advanced programs of your own, using the 
SoftCard and CP/M. Even with the RAMCard in 
place, you can still access your ROM BASIC 
and monitor routines. 

JOIN THE SOFTCARD 
FAMILY. 

The RAMCard is just the 
latest addition to the SoftCard 
family — a comprehensive sys- 
tem of hardware and software 
that can make your Apple more 
versatile and powerful than you 
ever imagined. 

Your Microsoft dealer has all 
the exciting details. Visit him 
soon, and discover a great idea 
that keeps getting better. 

Microsoft Consumer 
Products, 400 108th Ave. N.E 
Suite 200, Bellevue, WA 98004. 
(206)454-1315. 



npfHMH 


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■ i is 1 ■ :§' : 
1 . 1 £ I l«f < 

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/HKADSDfT 

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Our incredible low prices 
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"lake an additional 2% off our listed prices, until December 24. 



16 K RAM KITS 13.95 

Set of 8 NEC 41 16 200 ns 
GUARANTEED ONE FULL YEAR. 

DISKETTES 

ALPHA DISKS® 21.95 

SINGLE SIDED, CERT.DOUBLE DENSITY 
40 TRACKS, WITH HUB-RING, BOX OF 10, 
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VERBATIM DATALIFE 

MD 525-01, 10, 16 26.50 

MD 550-01, 10, 16 44.50 

MD 577-01, 10, 16 34.80 

MD 577-01, 10, 16 45.60 

FD 32 OR 34-9000 36.00 

FD 32 OR 34-8000 45.60 

FD 34-4001 48.60 

DISKETTE STORAGE 

5 Vi" PLASTIC LIBRARY CASE 2.50 

8" PLASTIC LIBRARY CASE 3.50 

PLASTIC STORAGE BINDER W/lnserts 9.95 

PROTECTOR 5% " 21.95 

PROTECTOR 8" 24.95 

INTEGRATED 
COMPUTER SYSTEMS 

NORTHSTAR CALL 

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CALIF. COMPUTER SYSTEMS CALL 

MORROW DESIGNS CALL 

280 BYTE December 1981 



PRINTERS 

ANADEXDP9500 1295,00 

ANADEXDP9501 1295.00 

CENTRONICS 739 765.00 

C-ITOH 25 CPS PARALLEL 1440.00 

C-ITOH 25 CPS SERIAL 1495.00 

C-ITOH 45 CPS PARALLEL 1770.00 

C-ITOH 40 CPS SERIAL 1870.00 

C-ITOH TRACTOR OPTION 195.00 

EPSON MX-80 SCALL 

EPSON MX-80 F/T SCALL 

EPSON MX-1 00 GRAPHIC SCALL 

EPSON GRAPHICS ROM 90.00 

IDS-445G PAPER TIGER . 779.00 

IDS-460G PAPER TIGER 945.00 

IDS-560G PAPER TIGER 1195.00 

NEC SPINWRITER 3510 Ser.RO 2195.00 

NEC SPINWRITER 3530 Par.RO 2195.00 

NEC SPINWRITER 7710 Ser.RO 2645.00 
NEC SPINWRITER 7730 Par.RO .2645.00 

NEC SPINWRITER 7700 D Sellum 2795.00 

NEC SPINWRITER 3500 Sellum 2295.00 

OKIDATAMICROLINE80 . .389.00 

OKIDATAMICROLINE82A 549.00 

OKIDATAMICROLINE83A 849.00 

OKIDATAMICROLINE84 1199.00 

QUME9/45 2149.00 

MALIBU 200 DUAL MODE 2695.00 

CORVUS 

FOR S-100, APPLE OR TRS-80 
MOD l,ll 

Controller, Case/P.S, Operating System, 
A&T. 

5 Megabytes 3245.00 

10 Megabytes 4645.00 

20 Megabytes 5545.00 

MIRROR BACK-UP 725.00 



APPLE SOFTWARE 

MAGIC WINDOW Word Processor .89.00 

MAGIC WAND 275.00 

WORDSTAR 259.00 

MAILMERGE(Req. WORDSTAR) .90.00 

SPELLSTAR(Req.WORDSTAR) 169.00 

DATASTAR 199.00 

EXPEDITER II Applesoft Compiler , 89.00 

PFS: PERSONAL FILING SYSTEM 79.00 

PFS: REPORT GENERATOR 79.00 

ASCII EXPRESS Terminal Program 59.95 

Z-TERMCP/M® Comm. Software 89.95 

MICROSOFT FORTRAN 165.00 

MICROSOFT COBOL 550.00 

DB MASTER 3.0 ... 179.00 

VISICALC3.3 169.00 

VISIPLOT 149.00 

VISIDEX 169.00 

CCA DATA BASE MANAGER 99.00 

A-STAT COMP. STATISTICS PKG. 1 1 9.00 



APPLE HARDWARE 

VERSA WRITER DIGITIZER 249.00 

ABT APPLE KEYPAD 119.00 

MICROSOFT Z-80SOFTCARD 299.00 

MICROSOFT RAMCARD 1 70.00 

VIDEX 80x24 VIDEO CARD 299.00 

VIDEX KEYBOARD ENHANCER 99.00 

M&R SUPERTERM 80 x 24 Video Bd.31 5.00 

NEC 12" GREEN MONITOR 199.00 

SANYO 12" MONITOR(B&W) 249.00 

SANYO 1 2" MONITOR(Green) 269.00 

SANYO 13" COLOR MONITOR ...469.00 
SSM AIO BOARD (INTERFACE)A&T 165.00 
SSMAIO BOARD flNTERFACEKIT 135.00 
ZENITH 1 3" HI-RES. Green MON. .1 39.00 

Circle 16 on inquiry card. 



MOUNTAIN HARDWARE 



CP/M SOFTWARE 



TRS-80 MOD I HARDWARE 



CPS MULTIFUNCTION BOARD 209.00 

SUPERTALKERSD200 259.00 

ROMPLUSW/KEYBOARD FILTER 179.00 
ROMPLUSW/O KEYBOARD FILTER 130.00 
KEYBOARD FILTER ROM . . 49.00 

COPYROM 49.00 

MUSIC SYSTEM 459.00 

ROMWRITER 149.00 

APPLE CLOCK 252.00 

A/D + D/A 299.00 

EXPANSION CHASSIS 625.00 



CALIF. COMPUTER SYSTEMS 

S-100 BOARDS 

2200A MAINFRAME 359.00 

2032A 32K STATIC RAM ...599.00 

2065C64K DYNAMIC RAM 499.00 

2422 FLOPPY DISK CONT.& CP/M® 339.00 
2710 FOUR SERIAL I/O . 249.00 

2718 2 SERIAL/2 PARALLEL I/O 269.00 

2720 FOUR PARALLEL I/O 199.00 

2810Z-80CPU 249.00 

APPLE BOARDS 

771 0A Asynchronous Ser. Interface . 1 39.00 
771 2A Synchronous Ser. Interface 149.00 

7424A CALENDER CLOCK 99.00 

7728A CENTRONICS Printer Interface99.00 



APPLE GAME SOFTWARE 

COMPUTER QUARTERBACK 32.95 

THE WARP FACTOR 32.95 

CARTELS AND CUTTHROATS . 32.95 

TORPEDO FIRE 49.95 

THE SHATTERED ALLIANCE 49.95 

COMPUTER BASEBALL 32.95 

POOL 1.5 29.95 

ULTIMA -....33.95 

RASTER BLASTER 24.95 

FLIGHT SIMULATOR 27.95 

INTERNATIONAL GRAND PRIX . .25.95 
COSMO MISSION . 24.95 

SARGONII 28.95 

SHUFFLE BOARD 29.95 

TAWALA'S LAST REDOUBT 24.95 

GALAXY WARS 20.95 

ALIEN RAIN (AKAGALAXIAN) 20.95 

SNOGGLE(REQ. JOYSTICK) 27.95 

ALIEN TYPHOON 20.95 

APPLE PANIC . 24.95 

SPACE WARRIOR 20.95 

PHANTOMS FIVE 24.95 

VISTA COMPUTER CO. 

APPLE 40 Tk.Drive A40 (1 63K Bytes) 389.00 
APPLE 80 Tk.Drive A80 (326K Bytes) 549.00 
APPLE 160Tk.Dr.A160(652K Bytes) 799.00 

APPLE 80 COLUMN CARD 329.00 

APPLE 8 Inch Disk Drive Controller 549.00 



MICROSOFT BASIC-80 299.00 

MICROSOFT BASIC COMPILER 319.00 

MICROSOFT FORTRAN-80 369.00 

PEACHTREE SYSTEMS CALL 

MAGIC WAN DfRequires CP/M" ) 275.00 
WORDSTAR(RequiresCP/M® ) . . . .325.00 
MAILMERGE(Requires WORDSTAR) 110.00 
SPELLSTAR(Requires WORDSTAR) 199.00 

CALCSTAR 239.00 

DATASTAR 249.00 

SPELLGUARD 239.00 

CP/M is a registered trademark of Digital Research. 



MODEMS 

NOVATION CAT ACOUSTIC MODEM 1 45.00 
NOVATION D-CAT Direct Connect 1 55.00 
NOVATION AUTO-CAT AUTO ANS. 219.00 
NOVATION APPLE-CAT 349.00 

UDS 103 LP DIRECT CONNECT 175.00 

UDS1 03 JLP AUTO ANSWER 209.00 

D.C.HAYES MICROMODEM ll(Apple)299.00 
D.C.HAYES 100 MODEM(S-1 00) 325.00 
D.C.HAYES Smart Modem(RS 232) 249.00 
LEXICON LX-11 MODEM 109.00 

SUPPLIES 

AVERY TABULABLES 

1,000 3 Vz x 15/16 8.49 

3,000 3V 2 X 15/16 14.95 

5,000 3 1 / 2 x 15/16 19.95 

PAPER (Prices F.O.B. S.P.) 

9 1 /2 X 11 181b. white 3000 ct 29.00 

14 7/8 x 11 181b. white 3000 ct. 39.00 



PERCOM DATA SEPARATOR . 27.00 

PERCOMDOUBLERII . . .159.00 

DOUBLE ZAP II/80 45.95 

TANDON 80 TRACK DISK DRIVE . 429.00 
TANDON 40 TRACK DISK DRIVE 299.00 
LNWDOUBLERW/DOSPLUS3.3D 159.00 



TRS-80 SOFTWARE 

NEWDOS/80 2.0MODI 139.00 

LAZY WRITER MOD I 125.00 

PROSOFT NEWSCRIPT MOD I, III 99.00 

SPECIAL DELIVERY MOD I, III . 119.00 
X-TRA SPECIAL DELIVERY MOD I, 111 199.00 

TRACKCESS MOD I 24.95 

OMNITERMSMARTTERM.MODI.III 89.95 
MICROSOFT BASIC COMP.For Mod 1165.00 

MORROW DESIGNS 

FLOPPY DISK SYSTEMS 

Controller, P.S., Microsoft Basic, 
CP/M® , A&T 

DISCUS 2D(Single Drive— 500K) 869.00 
DISCUS 2D(Dual-Drive— 1 MEG) 1499.00 
DISCUS 2 + 2(Single Drive— 1 MEG)1 099.00 
DISCUS 2 + 2(Dual Drive— 2 MEG) 1 999.00 

HARD DISK SYSTEMS 



Controller, P.S., Microsoft Basic, 
CP/M® , A&T 

DISCUS M1 0(10 Megabytes) . . 3099.00 
DISCUS M26 (26 Megabytes) 3949.00 



We stock a complete line of computer covers, printer rib- 
bons, print wheels & NEC thimbles— CALL US FOR YOUR 
NEEDS. 



We built a reputation on our prices and your satisfaction. 




We guarantee everything we sell lor 30 days. II anything is 
wrong, jusl return the ilem and we'll make il righl. And. ol 
course, we'll pay the shipping charges. 

We accept Visa and Master Card on all orders. COD orders 
accepted up lo $300.00. 

Please add $2.00 lor standard UPS shipping andhandling 
on orders under 50 pounds, delivered in [he continental U.S. 
Call us lor shipping charges on items lhal weigh more than 50 
pounds. Foreign. FPO and APO orders please add 15% lor 
shipping. California residents add 6% sales tax. 

The prices quoted are only valid lor slock on hand and all 
prices are subject lo change without nolice. 



Circle 16 on inquiry card. 



(213)7060333 

31245 LA BAYA DRIVE, WESTLAKE VILLAGE, CALIFORNIA 91362 

BYTE December 1981 281 



System Notes 



1000-1730 
INITIALIZE 



1900-1997 
SET UP FOR 
NEW GAME 



2000-2550 
CREATE 
SITUATION 
AND DRAW 
SCREEN 



2560-2600 
PRINT TIME 





YES 



2650-2660 

PRINT 
"TIME OUT" 



2720-2730 

PRINT 
"WRONG" 




YES 



2800-2850 
SCORE POINT 



2740-2790 
PRINT SCORE 
FOR GAME 



Figure 1: Flowchart of the game of Left/Right. More details have been included for the portion of the program that determines 
whether the correct switch has been pushed. Line numbers refer to the program in listing 1. 



6809 SYSTEMS (^ 6809 SYSTEMS Q 6809 SYSTEMS (^ 6809 SYSTEMS 



Featuring the GIMIX maintrame with 30 amp C.V. terro-resonant power supply; fifteen 50 pin and eight 30 pin slot Mother Board: 

2 Mhz CPU with time of day clock & battery back-up, 1K RAM, 6840 programmable timer, provisions for 9511A or 9512 For lurlher informal™, pricing ana brochures, contact 

Arithmetic processors, and 4 PROM/ROM/RAM sockets that can hold up to 32KB of monitor or user software. -_^ ^^■■^^■■m. M 

VARIETY: you can have 32KB, b6KB, 128KB and up of static RAM. You can use 5" and/or 8" disk drives, single or double /77\ I^^mI jK mC 

density, single or double sided, and single or double tracking with GIMIX disk controllers You have a wide choice of serial or I J ■■111 il^^^W 

parallel I/O cards. ^CT \ Tl " Com P» n ^ <*•• *■»■ 

EXPANDABILITY: You can add memory, l/Os, Video or Graphics cards, Arithmetic processors, additional drive capacity, and other ^**» Ouaiiiy Electronic products since ms. 

hardware now or in the future to this SS50 bus structured system from GIMIX or other SS50 bus compatible manufacturers. 1337 WEST 37th PLACE, CHICAQO, IL 60609 

SOFTWARE VERSATILITY: GIMIX systems can use TSC's FLEX or UNIFLEX and MICROWARE'S OS-9 operating systems. A wide (312) 927-5510 • TWX 910-221-4055 

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QUALITY: All boards are assembled, burned-in, and tested and feature GOLD PLATED BUS CONNECTORS. Only top quality com 

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and all necessary instruction and documentation. Flex and Unillex are trademarks ol Technical Systems 

GIMIX designs, manufactures and tests, in-house, their complete line of products. Complete systems are available to fit your Consultants inc. 0S9 is a trademark ol Microware inc. See 

needs. Please contact the factory if you have any special requirements. Ineir ads lor 0,ne ' GIMIX compatible sotiware. 



GIMIX' and GHOST" are regislered trademarks 
ot GIMIX Inc. 



For GIMIX compatible software see Technical Systems Consultants ad page 193 



282 December 1981 © BYTE Publications Inc 



Circle 174 on inquiry card. 



Circle 166 on inquiry card. 




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Tough Ford vans offer payloads 
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EXCELLENT 
VAN MILEAGE 



ESTIMATED 
RANGE 

1043 (722) 



EST. EPA 

HWY»* EST. 

MPG** 
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Std. 4.9L (300 CID) Std 221-gal. tank plus 
Six with optional optlonal18-gal. aux tank 
overdrive trans on 136 wb. Total 40.1 gal. 



"Compare these estimates with others. Your 



mileage and range may differ depending on 
speed, distance and weather. Actual highway 
mileage and range will probably be less than 
estimated. California estimates lower. Range 
superiority due to larger gas tank size rather 
than better fuel economy. 
•Based on R. L. Polk & Co. cumulative 
registrations as of July, 1980. 



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VISA and MasterCard orders accepted. 

MTI 

VIDEO TERMINALS Price 

VT100 DECscope_ $ 1595 

VT132 DECtcope 1995 

ADM 3A (dumb terminal) 595 

ADM 5 (dumb with visual attributes) . 645 

ADM 31 (two page buffer) 1095 

ADM 32 (ergonomic ADM 31) * 

ADM 42 (eight page buffer avail.) * 

Tl 940 (two page buffer) 1795 

Tl "Insight Series 10" personal term. .. 695 

Hezeltine Executive 80 Model 20 1495 

Hezeltine Executive 80 Model 30 1715 

1410 (Hazeltine dumb terminal) 825 

1420 (dumb terminels) 895 

1421 (Consul 580 & ADM 3A comp.) . 850 

1500 (dumb terminal) 1045 

1510 (buffered) 1145 

1520 (buffered, printer port) 1395 

1552 (VT52 compatible) 1250 

HazBltine Esprit 695 

GRAPHICS TERMINALS 

VT 1 00 with graphics pkg 3250 

VT 125 (DEC graphics) 3280 

ADM 3A with graphics pkg 1 795 

ADM 5 with graphics pkg 1845 

300 BAUD TELEPRINTERS 

LA34-DA DECwriter IV 995 

LA34-AA DECwriter IV 1095 

LA36 DECwriter II 1095 

Teletype 43 10AAG 1045 

Teletype 4320AAK 1 195 

Diablo 630 RO 2295 

Diablo 1640 KSR 2775 

Diablo 1650 KSR 2835 

Tl 743 (portable) 1190 

Tl 745 (port/built-in coupler) 1485 

Tl 763 (port/bubble memory) 2545 

Tl 765 lport/bubble/b.i. coupler) 2595 

Tl "Insight Series 10/1" pers. term. ... 695 

600 BAUD TELEPRINTERS 

Epson MX-80 645 

Tl 825 KSR impact 1570 

Tl 825 KSR pkg 1795 

Tl 840 RO impact 895 

Tl 840 KSR impact 1145 

Tl 840 KSR pkg 1635 

1200 BAUD TELEPRINTERS 

Epson MX-100 995 

LA 120 RA (receive only) 2095 

LA 1 20 AA (forms package) 2295 

Tl 783 (portable) 1645 

Tl 785 (port/built-in coupler) 2270 

Tl 787 (port/internal modem) 2595 

Tl 810 RO impact 1545 

Tl 810 RO pkg 1795 

Tl 820 RO impact 1850 

Tl 820 RO pkg 2025 

Tl 820 KSR impact 2025 

Tl 820 KSR pkg 2195 

Lear Siegler 310 ballistic 1945 

2400 BAUD 

Dataproducts M200 (2400 baud) 2910 

DATAPRODUCTS LINE PRINTERS 

B300 (300 LPM band) 5260 

B600 (600 LPM band) 6776 

B900 (900 LPM band) 10220 

BP1500 11500 LPM band) 19700 

2230 (300 LPM drum) 8148 

2260 (600 LPM drum) 9979 

2290 (900 LPM drum) 13098 

ACOUSTIC COUPLERS 

A/J A242-A (300 baud orig) 242 

A/J 247 1300 baud orig) 315 

A/J 1234 (Vadic compatible) 795 

Vadic VA 341 3 1300/1 200 orig) 845 

Vadic VA 3434 (1 200 baud orig) 845 

MODEMS 

GDC 103 A3 (300 baud Bell) 395 

GDC 202S/T (1200 baud Bell) 565 

GDC 21 2-A (300/1 200 beud Bell) 810 

A/J 1256 (Vadic compatible) 825 

V A 1 03 ( 300 baud modemphone) .... 235 

VA 3451 (orig/ans triple modem) 885 

VA 3455 (1200 beud orig/ans) 770 

CASSETTE STORAGE SYSTEMS 

Tachtran 816 (ttore/forward) 1050 

Techtran 817 (store/for/speed up) 1295 

Techtran 818 (editing) 1795 

Techtran 822 (dual) 2295 

FLOPPY DISK SYSTEMS 

Techtran 950 (store/forward) 1396 

Techtran 951 (editing) 1996 

•Please call for quote 



mti 



Distributors, New York, New Jersey and Ohio. 

NewYork: 

516/482-3500, 212/895-7177. 518/449-5959 

Outside N. Y.S.: 800/645-8016 

New Jersey. 201/227-5552 

V Ohio: 216/464-6688 

284 December 1981 © BYTE Publications Inc 



System Notes. 



Case 



Switch 
Pressed 



Background 



Switch 
Hand 



Matching 
Bar Side 



Response is 



O(black) 






0(left) 


1 (right) 

1 



0(left) 
1 (right) 



1 



correct 
wrong 
wrong 
correct 



5(grey) 
5 
5 
5 



wrong 
correct 
correct 
wrong 



9 











wrong 


10 








1 


correct 


11 





1 





correct 


12 


I 


1 


1 


wrong 


13 


I 5 








correct 


14 


I 5 





1 


wrong 


15 


I 5 


1 





wrong 


16 


I 5 


1 


1 


correct 



If switch is pressed, use: BG(KPOS) = AND LR = LSW 

OR 
BG(KPOS)*0 AND LR*LSW 

If switch 1 is pressed, use: BG(KPOS) = AND LR^LSW 

OR 
BG(KPOS)*0 AND LR = LSW 

Table 2: Truth table for the logic behind the BASIC expressions in lines 2680 and 
2710 of listing 1. For example, if switch is pressed when in the right hand, and 
background is grey (meaning use the opposite hand), and the matching bar is on the 
left (case 7), then this is the correct response. 



Listing 1: The game of Left/Right. The program consists primarily of two nested 
loops: line 1900 marks the beginning of a new game, while line 2000 is the start of a 
new play. The program is written in Apple II Integer BASIC and should not be too 
difficult to implement on other machines. See table 3 for definitions of some of the 
BASIC commands peculiar to the Apple. 

REM 

LEFT/RIGHT 

TRUCK SMITH 3/9^88 



998 

991 REM 

992 REM 
999 REM 

1888 REM _ INITIALIZE 

1818 DIM BS<4>#C(8> 

1828 C< 1 >=1 

1838 C(2>=2 

1848 C<3>=4 

1858 C(4>=9 

1868 C<5>=13 

1878 C«6>=3 

1888 C';7";'=15 

1898 CX8>=11 

1188 SW8=-16287 

1118 SH1=- 16286 

1128 TIHE=588 

1138 HS=0 

1439 REM 

1498 REM PRINT INSTRUCTIONS 

1588 TEXT 

1518 CALL -936 

1528 TAB 15 

1538 PRINT "LEFT/RIGHT" 



■1738 



Listing 1 continued on page 286 



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HORIZON II 

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HRZ-2-64DD, List $4195 

HRZ-2-Q32, List $3995 

HRZ-2Q64, Lisi $4495 

NEW.. .NORTH STAR ADVANTAGE. CALL 

DYIMABYTE 

List Less 30% 

ALTOS 

PLEASE CALL FOR PRICES 

SUPERBRAIN 

By INTERTEC 




64KDD $2695 

64K QD $2995 

DSS-10MEG $3195 

INTERTUBE $725 

Emulator $725 



CROMEMCO 



CS2, List $4695 . 
CS3, List $7995. 



our price $3549 
our price $6349 

data 
systems 

Z-89 .... List 

$2895 

OUR PRICE 

$2139 



Intersystems CALL FOR PRICES 




TERMINALS 

TeleVideo 




Televideo 910 


$579 


912C 


$659 


920C 


. . $729 


950 


$945 



SOROC 




Soroc IQ120 $689 

10.130 $579 

IQ135 $719 

IQ135w/g $789 

IQ140 $1049 

HAZELTINE 

1420 CALL 

1500 $789 

1510 CALL 

HAZELTINE ESPIRIT 

ZENITH Z19 $719 



Most items in stock lor immediate delivery Factory sealed cartons. 
w/tull factory warranty NYS residents add appropriate sales tax 
Prices do not include shipping. VISA and Master Charge add 3% 
C.0.0. orders require 25% deposit Prices subject to change without 
notice 



PRINTERS 

m 

CENTRONICS 

739-1 $749 

739-3 $799 

704-11 parallel $1569 

709-9 $1519 

TI810 




810 Basic $1289 

810 Full Option $1599 

820 RO Basic $1545 

820 KSR Basic $1739 



NEC 7510 $2395 

7530 ■ $2395 

Diablo 630 $2049 



PaperTiger 445G $739 

460 $799 

460G $839 

560G $1099 

Epson CALL FOR PRICES 



DISKSYSTEMS 



MORROW 




Discus 2D $849 

Dual Discus 2D $1389 

2 + 2 $1199 

M-26 $3599 

M-10 $2999 



COMPUTERS WHOLESALE 

P.O. Box 144 Camillus, N.Y. 13031 



Circle 95 on inquiry card. 



In N.Y. call 31 S - 472-2582 



Circle 294 on inquiry card. 



SORT 

EASIER 

QUICKER 

BETTER 

WITH 

MAGSORT 



Now there is MAGSORT '", the first full 
featured Sort/Select/Merge program spe- 
cifically designed to take the pain out 
of sorting. 

EASIER 

Interfacing MAGSORT to your CBASIC, 
Microsoft BASIC, Pascal/MT+, PL/1-80, or 
Fortran-80 programs is a snap. Two simple 
statements do it all. No dedicated memory, 
relocation, or special interfacing is required 
- not even in CBASIC. 

And running MAGSORT stand alone is 
just as simple. The easy-to-use utility pro- 
gram asks all the questions so you don't 
have to remember a dictionary full 
of commands. 

QUICKER 

MAGSORT is written in 8080/Z80 
assembler and uses a unique proprietary 
technique that allows the entire user mem- 
ory space to be utilized for buffering. This 
provides the fastest possible sorting and 
optimizes MAGSORT for large files. 

BETTER 

MAGSORT is better than super! Its 
unmatched features make it the sort for 
today's sophisticated systems. 

At $250, MAGSORT may cost a little 
more than some other sorts, but it quickly 
pays for itself with convenience, speed 
and versatility. And, like all MAG software 
products, MAGSORT includes our free one 
year support service. 



ruiAG 



Micro Applications Group Dept. 101 
20201 Sherman Way, Suite 205 
Canoga Park, CA 91306 

Please send more information about 
MAGSORT today. □ 

I would like to know more about your 
other programs too. D 



Name . 



. Title . 



Address 



City. 



. State . 



-Zip 



CBASIC is a trademark ul Compiler Systems Pascal/Ml + is a 
trademark al MT Microsystems PL/I-BQ is .1 trademark of 
Digital Research Fortran-80 is a trademark ol Micrusoll 



System Notes. 



1 540 

1556 
1569 
1570 
1588 

1590 

1S00 

1 6 1 
1620 
1630 
1640 
1650 
1660 
1670 
1680 
1690 

1700 

1710 
1720 
1730 
1999 

1 900 

1910 
1915 
1920 
1930 
1940 
1 950 
I960 
1970 
1980 
1996 
1995 
1996 
1997 
1999 

2000 
2010 

2019 
2020 
2030 
2048 
2058 
2060 
2878 
2079 
2080 
2898 

2100 

2110 
2111 
2112 
2114 
2119 
2120 
2130 
2139 
2140 
2150 



PRINl 

PRINT "THE OBJECT OF THIS SOME IS TO SEE IF" 

PRINT "VOLS KNOW V0UR LEFT FROM V0UR RI8HT. " 

PRINT 

PRINT "THE COMPUTER WILL DRAW fl COLORED BOH" 

PRINT "AND* AT THE BOTTOM OF THE SCREEN, THO" 

PRINT "COLORED BARS. VOL! MUST DETERMINE" 

PRINT "WHETHER THE LEFT OR RI8HT HAND BAR" 

PRINT "HATCHES THE BOX'S COLOR AND PUSH THE" 

PRINT "CORRESPOND I N6 BUTTON. HOHEUER, IF THE" 

PRINT "BACKGROUND AROUND THE BOX IS BREY, VOU" 

PRINT "MUST PUSH THE OTHER BUTTON." 

PRINT 

PRINT "THE ROUND CONTINUES UNTIL VOU HAKE A" 

PRINT "MISTAKE OR THE TIMER RUNS OUT." 

PRINT 

PRINT "THE TIMER STARTS AT 588. IT DOES NOT" 

PRINT "RUN WHILE THE COMPUTER IS DRAW INS." 

PRINT 

PRINT 

REM — — — 

REM INITIALIZE FOR NEW PLAVER -1997 

9C=0 

THE 10 

PRINT "WHEN VOU ARE READY" 

PRINT "PRESS THE BUTTON IN VOUR LEFT HAND" 

IF PEEK CSW8>>127 {HEN 1970 

IF PEEK (SW1»127 THEN 1990 

GOTO _ 194a 

LSH=0 

60T0 1995 

LSW=1 

8R 

CALL -936 

T=TIME 

REM 

REM CHOOSE MATCH INS COLOR -2818 
LR= RND C2> 

REM 

REM CHOOSE POSITION -2878 

HP0S= RND <2> 

X=5+HPOS*20 

UP0S= RND C2> 

V=i+UPQS*19 

KPGS=HP0S*2+UP0S+1 

REM 

REM CHOOSE BACKGROUND -2118 
FOR 1=1 TO 4 
BGCI>= RND C2>*5 
NEXT I 

REM 

REM CHOOSE COLOR PAIR -2114 
LC= RND <7>+i 

REM 

REM SIMPLIFY -2338 
IF SC>26 THEN 2348 

REM 

REM SIMPLIFY COLOR -2168 

IF SC HOD 6=8 THEN LK= RND <3>*2+l 

Listing 1 continued on page 290 



286 December 1981 © BYTE Publications Inc 



Incorporated 




hjcacccuuy 



aruiausiceA/ 




a new generation 

in data base 

management technology 



not limited 

to relational, tabular, 
flat-tile structures 



not limited 

to hierarchical structures 



not limited 

to CODASYL network 
structures 



The structures above are mere subsets of the capabilities of MDBS III. 
Far beyond these, MDBS III provides valuable innovations available in no other system! 

Unprecedented POWER! FLEXIBILITY! PORTABILITY! 

For serious application development, MDBS III offers major advantages in these seven key areas: 

Available for Minis and Micros 

Availability for numerous 8 and 16-bit 
micros, as well as for minis, provides 
standardized approach to data handling. 

Allows extensive portability of application 
systems. . .from the Z-80 to the PDP-11. 



Extraordinary data structuring 

Unmatched flexibility for relating records to 
each other with ease. 

Automatic data compression where desired. 

Up to 255 record types per schema. 

High-level query language 

Automatically generates desired report or 
data file with a single statement. 

Language is English-like, non-procedural, 
and has report writing capabilities. 

Extensive performance control 

Gives application designer extensive 
control over record placement. . . includes 
automatic clustering and CALC features. 

For highest performance, a streamlined 
DML. . .over 20 host language interfaces 
available. 

All processing is data-dictionary driven. 

Data security and integrity 

User passwords and optional data 
encryption. 

Comprehensive access code facility for 
automatic security enforcement. 

Automatic range checking. 



Setting standards of excellence for data base 
software. . .worldwide. 



/Micro 
Data Hnsc 
Systems, inc. 

Box 248 

Lafayette, Indiana 47902 

31 7-448-1 61 6/TWX 810-342-1881 

Dealer/distributor/ OEM inquiries invited. 



True multi-user capabilities 

Supports multiple concurrent users of the 
same data base. 

Supports both active and passive locking. 

Automatic transaction logging 

Automatically logs all transactions after last 
back-up. 

Selective restoration of data base in event of a 
crash. 

Allows surveillance of user activities. 



For the full story about the finest 
application development tool existing 
in the mini-micro world. ...call, write, 
or TWX us today! 



□ Yes, please send me a copy of the MDBS III brochure. 

□ Please send me the complete MDBS II manual set including 
manuals for MDBS III, RTL, QRS, and DMU plus tutorial 
materials. Check for $85.00 enclosed. (Indiana residents please 
add $3.40 for Indiana tax.) 




Name 



(Pi 



print) 



Title 



Company 
Address _ 



City _ 
Phone 



(State) 



(Zip) 



MAIL TO: Micro Data Base Systems, Inc. 
P.O. Box 248-B 
Lafayette, IN 47902 



Circle 255 on inquiry card. 



gift of the futurtj- ■ 
from BYTE Books 







Siapcia's Oipcwit (Jellap 






Inversions: A Catalog of 
Calligraphic Cartwheels 

by Scott Kim 

Illusion.. .calligraphy.. .visual 
magic — Scott Kim's new book 
delights the eye and enchants 
the mind. Filled with intriguing 
designs, words that read the 
same right side up and upside 
down, words within words, and 
unexpected symmetries, these 
compositions create a fresh way 
to look at the beauty of alpha- 
bets, mathematics and design. 

ISBN 0-07-034546-5 
128 pages; softcover 
8.95 



Digital Harmony 

On the Complementary of 
Music and Visual Art 

by John Whitney 

Here we have a major new work 
that explores a special union of 
music and computer graphics 
and defines a new frontier be- 
tween sight and sound, integrat- 
ing the two to create a new art 
form. Digital Harmony lays 
the foundation for an audio- 
visual art made possible by com- 
puters. It is a must for all those 
interested in art, music, video, 
film, computers, education, arti- 
ficial intelligence, psychology, 
and futurology. 

ISBN 07-070015-X 
240 pages; hardcover 
21.95 



BASIC Scientific 
Subroutines, Vols. I 
and II 

Valuable programs for 
professional and hobbyist 

by Fred R. Ruckdeschel 

Designed for the engineer, scien- 
tist, experimenter, and student, 
this series presents a complete 
scientific subroutine package fea- 
turing routines written in both 
standard Microsoft and North 
Star BASIC. 

• Volume I covers plotting, com- 
plex variables, vector and matrix 
operation, random number gen- 
eration, and series approxima- 
tions. 



• Volume II includes least- 
squares approximation, special 
polynomial functions, approxi- 
mating techniques, optimization, 
roots of functions, interpolation, 
differentiation, and integration. 

Volume I 

ISBN 0-07-054201-5 

336 pages; hardcover 

19.95 

Volume II 

ISBN 0-07-054202-3 

800 pages; hardcover 

23.95 



Threaded Interpretive 
Languages 

How to implement FORTH on 
your Z80 

by Ronald Loeliger 

This book develops an interac- 
tive, extensible language with 
specific routines for the Zilog 
Z80 microprocessor. With the 
core interpreter, assembler, and 
data type defining words covered 
in the text, it is possible to de- 
sign and implement programs 
for almost any application and 
equivalent routines for different 
processors. 

ISBN 0-07-038360-X 
272 pages; hardcover 
18.95 



The Brains of Men and 
Machines 

Human models for computer 
design 

by Ernest W. Kent 

In this rare book, the ever-in- 
creasing relationship between 
man and machine is freshly ex- 
amined — a relationship, Kent 
concludes, that is being restudied 
in the light of man's own neuro- 
logical self-image. The Brains 
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sects" the brain to provide new 
insights into computer design 
and artificial intelligence. 

ISBN 0-07-034123-0 
304 pages; hardcover 
15.95 



Microcomputer 
Structures 

Digital electronics, logic design 
and computer architecture 

by Henry D'Angelo 

Microcomputer Structures 
introduces computer users with 
little or no background in digital 
hardware to the basic structures 
used in microcomputer design 
and interfacing. As a resource 
and textbook, this book will as- 
sist programmers and system 
analysts, engineers and scien- 
tists, managers and students. In- 
structor's Manual is also 
available. 

ISBN 0-07-015294-2 

394 pages; hardcover 

18.95 

Instructor's Manual 

ISBN 0-07-015298-5 

101 pages; softcover 

8.95 



Ciarcia's Circuit Cellar, 
Vols. I and II 

Practial uses for home 
computers 

by Steve Ciarcia 

Imaginative and practical, 
Ciarcia's Circuit Cellar in 
two volumes details a variety of 
microcomputer projects. You'll 
find them to be a collection of 
the best articles from the popu- 
lar series in BYTE magazine. 

• Volume I includes D/A conver- 
sion, programming EPROMs, AC 
remote controlled appliances, 
digitized speech, touch input 
video display. 

• Volume II covers projects such 
as building a computer-con- 
trolled home security system, 
computerizing appliances, trans- 
mitting digital information over 
a beam of light, input/output ex- 
pansion for the TRS-80. 

Volume I 

ISBN 0-07-010960-5 

125 pages; softcover 

8.00 

Volume II 

ISBN 0-07-010963-X 

224 pages; softcover 

12.95 



Circle 469 on inquiry card. 



Build Your Own Z80 
Computer 

Design Guidelines and 
Application Notes 

by Steve Ciarcia 

For the engineer, computer 
technician, student, and anyone 
interested in building a com- 
puter rather than buying one, 
this practical guide shows how to 
build a working computer based 
on the Zilog Z80 microprocessor. 
Each computer subsystem is ful- 
ly explained and supported by 
proven design and testing infor- 
mation. 

ISBN 0-07-010962-1 
330 pages; softcover 
15.95 

Beyond Games: Systems 
Software for Your 6502 
Personal Computer 

Creating programs for the 
Apple, Atari, Challenger and 
PET computers 

by Kenneth Skier 

At last, a complete programming 
guidebook. A self-contained 
course in structured program- 
ming and top-down design, this 
book presents a powerful set of 
tools for building an extended 
monitor, disassembler, hexadeci- 
mal dump routine and text 
editor programs. 

ISBN 0-07-057860-5 
440 pages; softcover 
14.95 

Beginner's Guide for 
the UCSD Pascal 
System 

The most popular Pascal ver- 
sion explained by its creator 

by Kenneth L. Bowles 
Written by the originator of the 
UCSD Pascal System, this infor- 
mative book is an orientation 
guide to the System. For the 
novice, this book steps through 
the System, bringing the user to 
a sophisticated level of expertise. 
Once familiar with the System, 
the reader will find the Guide an 
invaluable reference tool for 
creating advanced applications. 

ISBN 0-07-006745-7 
204 pages; softcover 
11.95 



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Add 75c per book to cover shipping costs: 

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ORDER TOLL FREE 800/258-5420 



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JZ 




MODEMS 

All Modems connect to any 
RS232 Computer or Terminal! 

1200 Baud and 300 Baud-Bell 212A 

Style. Penril 300/1200 $779 

Originate/answer/auto-answer. Full duplex. 
RS232. Phone line connection via standard 
phone jack. 1 yr. warranty. 
Auto-dial option $350 

300 Baud Phone Link $179 

Originate/answer. Sleek, low profile. 15ozs. Half/ 
full duplex. Self test. RS232. Light displays for 
On Carrier. Test, Send&Receive Data. 1 yr. 
warranty. 

300 Baud. USR-330D $339 

Originate/answer/auto-answer. Phone line 
connection via standard jack. 1 yr. warranty. 

300 Baud. USR-330A $399 

Same as USR-330D PLUS Auto-Dial. Call for 
quote and technical information on higher 
speed modems and miltiplexors. 

Printing Terminals 

The new generation of printing terminals 
from General Electric. 
30/60 CPS.GETerminet2030 .... $929 

110/300/60/1200 Baud. User selectable lines 
per inch and chars, per inch. True descenders 
and underlining. Up to 217 cols, per line. Top of 
form, vert, and hor. tabs. Friction feed std., 
tractor feed opt. Answerback. 1 yr. warranty on 
parts. Nationwide servicing. Extremely com- 
pact. 15 in. paper. Only 22 lbs. Built in text editor 
with 16k text editor optional. SUPERIOR TO DEC 
LA34AA at lower cost. 
120/150 CPS. 

GE Terminet 2120 $1,699 

Housed in same compact package as the 2030 
with all the features of the 2030 PLUS 150 char, 
per. sec. print rate. 
Letter Quality. NEC 7720 

KSR with keyboard $2,695 

55 CPS. RS232 and Centronics parallel. Inter- 
changeable print thimbles for a wide variety of 
perfect, letter quality output. 

CRT's 

Televideo (Lear Seigler, Hazeltine 

and ADDS equivalent) $584 M^ „__ 

24 x 80. RS232. Numeric keypad. Non-glare , ■ Ittlf 

screen. Printer Port. Function keys. ' 

Televideo 950 $959 

Green, Non-glare screen. RS232. Detachable 
keyboard. Advanced editing with wraparound. 
Smooth scrolling. 15 baud rates. Protected 
fields. Underlining. Split screen. Fully program- 
mable function keys. 15 graphics characters. 
Self test. 25th status line. Buffered printer port. 
14 x 10 high resolution character display. Tilta- 
ble screen. Nationwide service from General 
Electric. 

Televideo 91 2C... $759 

Televideo 920C....S792 
Visual Technology-Visual 100 

(DEC VT100 Emulator) $1,399 

All the features of the DEC VT100 INCLUDING 
Advanced Video Features and Non-glare 
screen. ' . 

Printers 

OKIDATA Mircroline 82A. 120 CPS. 

80/132 Columns per line $529 

User selectable char. Sizes. Top-of-form bi-direc- 
tional. Short line seeking print techniques for 
greater throughput. RS232 & Centronics parrellel 
interfaces. 

Letter Quality, NEC 7710 RO. . . $2,395 
Same features as the 7720KSR listed above but 
without keyboard. 

Letter Quality, NEC 3510 RO. . . $1,499 
Like the 7710 RO but 30 CPS. 



VISA/MASTERCARD Accepted. Corporation and In- 
stitution purchase orders accepted. Leasing rates 
available on request. All equipment is shipped with a 
10-day money back guarantee. We otter full service, 
on-site maintenance plans on all equipment. All equip- 
ment in stock. 

U.S. ROBOTICS inc. 



1 >l )3 N WABASH RALES (313) 3-4B-b65n 

SLJITE I7IB GENERAL OFFICES !3I3) 34S-5S5I 

CHICAGO, ILL 60S01 SERVICE 1313)733-0497 






346 -565 1 
733-0497 



System Notes , 



2169 
2169 
2179 
2180 
2190 
2199 
2200 
2210 
*220 



2230 
2240 
2250 
2260 
2270 
2280 
2290 

2300 

2310 
2320 



2330 
2339 
2340 
2350 
2360 
2370 
2380 
2390 
2400 
2410 
2420 
2430 
2440 
2450 
2459 
2460 
2470 
2480 
2490 
2500 
2509 
2510 
2520 
2530 
2540 



LC=LK 

REH 

REM SIHPLIFV POSITION -2190 

IF SCX18 THEN V=9 

IF SCO THEN X=15 

REH 

REH SIHPLIFV BACKGROUND -2330 

IF SC>2 THEN 2260 

FOR 1=1 TO 4 

BG< I >=0 

NEXT I 

60T0 2340 

IF SOU THEN 

FOR 1=2 TO 4 

BG< I >=BG< 1 > 

NEXT I 

GOTO 2348 

IF SO20 THEN 

B6<:2>=BG<1> 

BG<4>=66<3> 

REH 



2310 



2340 



REH DRAW SCREEN -2550 

REH DRAW BACKGROUND -2450 

FOR 1=0 TO 19 

COLOR=BGC 1 > 

ULIN 0,18 AT 19-1 

C0L0R=BG<:2> 

ULIN 19,37 AT 19-1 

C0L0R=BG(3> 

ULIN 0,18 AT 20+1 

C0L0R=BG<4) 

ULIN 19,37 AT 20+1 

NEXT I 

REH 

REH DRAW BARS -2500 
COLOR=C<LC> 
HLIN 5,16 AT 39 
COLOR=tXLC+l> 
HLIN 25,36 AT 39 

REH 

REH DRAW BOX -2550 
COLOR=C(LC+LR) 
FOR 1=0 TO 16 
HLIN X,X+11 AT V+I 
NEXT I 



2559 REH 



256a 
2580 
2590 
2600 
2610 
2620 
2630 
2640 
2650 
2660 
2669 
2670 REH 



REH WAIT -2660 

UTAB 22 

TAB 30 

PRINT Ti" " 

IF PEEK >CSW0J>>127 THEN 2670 

IF PEEK CSW1»127 THEN 2700 

T=T-1 

IF T>0 THEN 2560 

PRINT "THE CLOCK RAN OUT" 

GOTO 2740 

REH 



SWITCH -2690 

Listing 1 continued on page 292 



290 December 1981 © BYTE Publications Inc 



Circle 417 on Inquiry card. 



CQMPLITRQNICS 



C. 



EVERYTHING FOR YOUR TRS-80* • ATARI* • APPLE* • PET* 

TRS-80 is a trademark of the Radio Shack Division of Tandy Corp. - 'ATARI is a trademark of Atari Inc. - 'Apple is a trademark of Apple Corp. - 'Pet is a trademark of Commodore 



BUSINESS PAC 100 




Software 



100 Ready-To-Run 
Business Programs 



(ON CASSETTE OR DISKETTE) Includes 110 Page Users Manual 5 Cassettes (Or Diskettes) 

Inventory Control Payroll Bookkeeping System Stock Calculations 

Checkbook Maintenance Accounts Receivable.. ..Accounts Payable 



USINESS 100 PROGRAM LIST 



1 RCILE78 Interest Apportionment by Rule of the 78s 

2 ANNUI Annuity computation program 

3 DATE Time between dates 

4 DAYYEAR Day of year a particular date falls on 

5 LEASE1NT Interest rate on lease 

6 BREAKEVM Breakeven analysis 

7 DEPRSL StraightJine depreciation 

8 DEPRSY Sum of the digits depreciation 

9 DEPRDB Declining balance depreciation 

10 DEPRDDB Double declining balance depreciation 

I I TAXDEP Cash flow vs. depreciation tables 

12 CHECK2 Prints NEBS checks along with daily register 

13 CHECKBKI Checkbook maintenance program 

14 MORTGAGE/ A Mortgage amortization table 

1 5 MULTMON Computes time needed for money to double, triple, 

16 SALVAGE Determines salvage value of an investment 

1 7 RRVARIN Rate of return on investment with variable inflows 

18 RRCONST Rate of return on investment with constant inflows 

19 EFFECT Effective interest rate of a loan 

20 FVAL Future value of an investment (compound interest) 

21 PVAL Present value of a future amount 

22 LOAMPAY Amount of payment on a loan 

23 REGWTTH Equal withdrawals from investment to leave over 

24 SIMPDISK Simple discount analysis 

25 DATEVAL Equivalent & nonequivalent dated values for oblig. 

26 ANNUDEF Present value of deferred annuities 

27 MARKUP % Markup analysis for items 

28 SINKFUND Sinking fund amortization program 

29 BONDVAL Value of a bond 

30 DEPLETE Depletion analysis 

31 BLACKSH Black Scholes options analysis 

32 STOCVAL1 Expected return on stock via discounts dividends 

33 WARVAL Value of a wan-ant 

34 BONDVAL2 Value of a bond 

35 EPSEST Estimate of future earnings per share for company 

36 BETAALPH Computes alpha and beta variables for stock 

37 SHARPE1 Portfolio selection model-i.e. what stocks to hold 

38 OPTWRITE Option writing computations 

39 RTVAL Value of a right 

40 EXPVAL Expected value analysis 

41 BAYES Bayesian decisions 

42 VALPRINF Value of perfect information 

43 VALADINF Value of additional information 

44 UTILITY Derives utility function 

45 SIMPLEX Linear programming solution by simplex method 

46 TRAMS Transportation method for linear programming 

47 EOQ Economic order quantity inventory model 

48 QCIECJE1 Single server queueing (waiting line) model 

49 CVP Cost-volume-profit analysis 

50 CONDPROF Conditional profit tables 

51 OPTLOSS Opportunity loss tables 

52 FQUOQ Fixed quantity economic order quantity model 

NAME DESCRIPTION 

53 FQEOWSH As above but with shortages permitted 

54 FQEOQPB As above but with quantity price breaks 

55 QUEUECB Cost-benefit waiting line analysis 

56 NCFAMAL Met cash-flow analysis for simple investment 

57 PROF1ND Profitability index of a project 

58 CAP! Cap. Asset Pr. Model analysis of project 

Circle 177 on Inquiry card. 



59 WACC Weighted average cost of capital 

60 COMPBAL True rate on loan with compensating bal. required 

61 DISCBAL True rate on discounted loan 

62 MERGAMAL Merger analysis computations 

63 FIMRAT Financial ratios for a finn 

64 MPV Met present value of project 

65 PRIMDLAS Laspeyres price index 

66 PRIMDPA Paasche price index 

67 SEASIMD Constructs seasonal quantity indices for company 

68 TIMETR Time series analysis linear trend 

69 TIMEMOV Time series analysis moving average trend 

70 FUPRINF Future price estimation with inflation 

71 MAILPAC Mailing list system 

72 LETWR1 Letter writing system-links with MAILPAC 

73 SORT3 Sorts list of names 

74 LABEL I Shipping label maker 

75 LABEL2 Maine label maker 

76 BUSBUD DOME business bookkeeping system 

77 TIMECLCK Computes weeks total hours from timeclock info. 

78 ACCTPAY In memory accounts payable system-storage permitted 

79 INVOICE Generate invoice on screen and print on printer 

80 INVENT2 In memory inventoiy control system 

8 1 TELDIR Computerized telephone directory 

82 T1MUSAM Time use analysis 

83 ASSIGN Use of assignment algorithm for optimal job assign. 

84 ACCTREC In memory accounts receivable system-storage ok 

85 TERMSPAY Compares 3 methods of repayment of loans 

86 PAYNET Computes gross pay required for given net 

87 SELLPR Computes selling price for given after tax amount 

88 ARBCOMP Arbitrage computations 

89 DEPRSF Sinking fund depreciation 

90 UPSZONE Finds UPS zones from zip code 

91 ENVELOPE Types envelope including return address 

92 AUl"OEXP Automobile expense analysis 

93 INSF1LE Insurance policy file 

94 PAYROLL2 In memoiy payroll system 

95 DILANAL Dilution analysis 

96 LOANAFFD Loan amount a borrower can afford 

97 RENTPRCH Purchase price for rental property 

98 SALELEAS Sale-leaseback analysis 

99 RRCONVBD Investor's rate of return on convertable bond 
100 PORTVAL9 Stock market portfolio storage-valuation program 



D CASSETTE VERSION 
D DISKETTE VERSION 
D TRS-80* MODEL II VERSION 



$99.95 

$99.95 

$149.95 



ADD $3.00 FOR SHIPPING IN UPS AREAS 
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h^ATVCfvlATOtti. APR_JCLATCjrjS «»./*-£ " 




50 N. PASCACK ROAD 
SPRING VALLEY, NEW YORK 10977 




HOUR 
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(9 14) 425-1535 



System Notes . 



2689 
2690 
2699 
2700 
2710 
2719 
2720 
2730 
2739 
274© 
2750 
2760 
2770 
2780 
2790 
2799 
2886 
2810 
2820 
2830 
2840 
2850 



IF (B6CKPO5>=0 AND LR=LSH) OR < BG< KPOS >#0 AND LR#LSH> THEN 2800 
bOTO 2720 

REH 

REH SWITCH 1 -2720 

IF CB6CKPOS>=0 AND LR#LSW> OR < BG< KPDS >#0 AND LR=LSW> THEH 2800 

REM 

REM WRONG -2730 

PRINT "SORRV - WRONG BUTTON" 

REM 

REH DELAY -2790 

IF HS<SC THEN HS=SC 

PRINT "YOUR SCORE ";SC;" HIGH SCORE "jHS;" TIME "iT 

FOR 1=1 TO 400 

NEXT I 

GOTO 1900 

REH 

REH RIGHT -2850 

SC=SC+1 

UTflB 22 

TAB 10 

PRINT SCi" " 

GOTO 2000 



Text continued from page 278: 

screen; the bars at the bottom change color. Suddenly, 
you are confronted with a screen that is half grey and half 
black. The box is on the screen's black side, so you ten- 
tatively press the button for the bar that matches the box. 
Correct again; the game continues. 

In this version of the game, play ensues until you make 
a mistake or until the time runs out (about 30 seconds). 
Your score is the number of correct answers. The highest 
score yet attained is 42 points. 

When your turn is finished, you hand the push buttons 
to the next player. Mixing them up makes no difference, 
since the program automatically determines which switch 
is in your left hand. 

I dreamed up the game and wrote the original program 
for my Apple II in one weekend. I tried it and then intro- 
duced it to my wife, who promptly topped my best score. 

I immediately reprogrammed the game to make it 
harder. I added the grey background, cut the screen first 
in half and then in quarters, and changed the bars' colors 
after every point. My wife's continued winning streak 
highlighted the futility of further changes. 

I can no longer demonstrate the program because my 
scores are too low to exhibit all of its features. My wife 
has assumed the task of demonstration. 

The game is easily learned, but not readily mastered. 
The rules are more easily demonstrated than described. 
Concentration and quick reactions to a complex set of 
stimuli are needed for a high score. 

The Trance 

To p/ay the game well, you must turn a conscious, 
well-considered response into a subconscious one. You 
must then avoid thinking about the individual responses. 

292 December 1981 © BYTE Publications Inc 



The phenomenon of perseveration, and the level of logic 
involved in the correct decision, add to the difficulty. 

Perseveration is the tendency to continue with the 
same response, regardless of the display. If the program 
gives you five 'lefts" in succession, your tendency is to 
react with a left for the next response. This forces your 
continued attention to the game; it is my hunch that this 
is an important factor in invoking the trance state. 

The level of logic insures that the responses are not 
simple. The first level occurs in the matching process; the 
second occurs in the reversal of handedness required 
when the background is grey. The logic could be deep- 
ened still a third level, through random changes in the 
box's shape (to a cross, for instance) to require yet 
another reversal of handedness. 

The trance state originates in the combined effects of 
these phenomena. The need for decisions makes constant 
attention essential, and the decisions are too complicated 
to be left to natural reactions. An interesting experiment 
would have the level of logic continue to deepen until a 
trance was no longer invoked. (It may be impossible, 
either with this game or in general.) I will discuss this and 
other possible modifications after discussing the program 
itself. 

The Program 

The original version of the program evolved naturally 
om mv erven situation: 



from my given situation: 



•I had an apple II, which could draw all sorts of colored 
pictures on my TV screen. 

•The Apple II comes with two push-button switches. 
•I knew I wanted to write a real-time computer game. 

Text continued on page 298 
Tables and listings continue on pages 294-296 



THE ORIGINAL MAGAZINE FOR 
OWNERS OF THE TRS-80 ™* MICROCOMPUTER 



* TRS-80" IS A TRADEMARK OF TANDY CORP. 



SOFTWARE 

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iCQmPJTRQMCS 



iwaTvewvrcAi. apcvejvtons se«=»vce" 



50 N. PASCACK ROAD 
SPRING VALLEY, NEW YORK 10977 

ONE YEAR SUBSCRIPTION $24 

TWO YEAR SUBSCRIPTION $48 

SAMPLE OF LATEST ISSUE $ 4 

START MY SUBSCRIPTION WITH ISSUE 

(#1 - July 1978 • #12 • June 1979 • #24 - July 1980 ■ 
NEW SUBSCRIPTION RENEWAL 



NEW TOLL-FREE 

ORDER LINE 

(OUTSIDE OF N.Y. STATE) 

(800) 431-2818 




HOUR 
24 ORDER 
LINE 

(914) 425-1535 




#30 - January 1981) 



CREDIT CARD NUMBER . 
SIGNATURE 



_EXP. DATE_ 



NAME. 



ADDRESS . 



_CITY_ 



.STATE _ 



.ZIP. 



*** ADD $12/YEAR (CANADA, MEXICO) - ADD $24/YEAR AIR MAIL - OUTSIDE OF U.S.A., CANADA & MEXICO *** 

Circle 176 on inquiry card. BYTE December 1981 293 



System Notes. 



Listing 2: Variable cross-references to the program in listing 1. 

B6- 1810 2100 2230 2230 2280 2320 2320 2330 2330 2370 2330 2410 2430 2680 2680 

2710 271a 

C- 1010 1020 1030 1043 1050 1063 1070 1080 1030 2470 2430 2520 

HPOS- 2030 2040 2070 

HS- 1130 2750 2750 2760 

I- 2030 2100 2110 2220 2230 2240 2270 2280 2233 2360 2380 2400 2420 2440 2450 
2530 2543 2550 2770 2780 

KPOS- 2070 2680 2688 2718 27 10 

LC- 2114 2i60 2470 2433 2520 

LK*- 2158 2163 

LR- 2810 2520 2680 2880 2710 2710 

LSW- 1378 1330 2680 2688 2718 2710 

SO 1910 2138 2150 2188 2133 2213 2268 2318 2758 2750 2760 2818 2818 2848 

SH8- 1100 1343 2610 

BW1- 1118 1350 2628 

T- 1337 2680 2630 2630 2640 2768 

TIME- 1128 1337 

yPOS- 2350 2060 2070 

K- 2040 2133 2540 2540 

V- 2060 2180 2548 



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C.O.R. Systems Inc. 
Controlled Data Recording Systems. Inc. 
7667 Vickers St.. San Diego. CA 92111 



Circle 333 on Inquiry card. 



Circle 230 on Inquiry card. 



Circle 55 on Inquiry card. 



ATTENTION 





HOW DOES A $299 BYTEWRITER-1 
STACK UP AGAINST A $650 EPSON MX- 

YOU DECIDE! 



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9514 Chesapeake Drive 
San Diego, CA 92123 
(714) 278-0633 
Outside CA call 
TOLL FREE (800) 854-1081 

TWX. 910-335-1269 

TRS-80 is a trademark of Radio Shack, Div. 

of Tandy Corp. 
Apple II is a trademark of Apple Computer, 

Inc. 
Atari 400 & 800 are trademarks 

of Atari, Inc. 
MX-80 is a trademark of 

Epson America, Inc. 

Jlrcle 272 on Inquiry card 



FEATURES 



BYTEWRITER-1 



EPSON MX-80 4 



Print speed 



60 lines per minute 



46 lines per minute 



Paper feed 

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Printhead — 100 million char. 
Drive Mech. — 10 million char. 
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System Notes 



Graphics Commands 

GR — Clears screen and sets low-resolution graphics mode; a 40 by 40 array of "bricks," with four lines of text at the bottom of the screen. 
Coordinates run from the upper left-hand corner: 0,0 is the upper left-hand corner; 0,39 the lower \e1Wnand corner; 
39,0 upper right; and 39,39 lower right. 

-1 

CALL - 936 — Clears text area of screen. 

VLIN A,B AT C — Draws a vertical line of bricks from A to B at the column specified by C. 
HLIN A,B AT C — Same as VLIN, but draws a horizontal line. 

COLOR = I — Sets color used for plotting until next COLOR = I is encountered. Values for I are as follows: 

1 red 9 orange 



blue 

purple 

green 



11 
13 

15 



pink 

yellow 

white 



Other Commands 

VTAB N — Vertical tab to row N on the screen before printing. 

TAB N — Horizontal tab to column N on the screen. This is a command, not a function, as in most BASICS. 

PEEK(- 16287) — Ascertains if switch has been pushed. If it has, the value returned is greater than 127; otherwise, it is less. 

PEEK(- 16286) — Same as PEEK(- 16287), but for switch 1. 

RND(N) — Returns a random integer between and N - 1 . 

Apple II Integer BASIC variable names may be of any length. 



Table 3: An explanation of some of the Apple Integer BASIC commands which may not be available on other microcomputers - 
useful when implementing the game of Left/Right on another machine. 



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296 December 1981 © BYTE Publications Inc 



Circle 102 on Inquiry card. 



SVA 
MAKING APPLES 

GROW 

RIGHT PRICE -RIGHT DELIVERY 



SVA originated 8" floppy disk controllers for the Apple 
in 1 979 based on 8 years of microcomputer consulting 
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Since then we have added four new memory systems 
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SVA products adhete strictly to industry computer 
srandatds. 

SVA makes yout data readable on other computers 
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by recording all data using standard IBM fotmots. 

Standatd Apple DOS, CP/M and Pascal are used to 
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continued support. 



SVA has delivered 2000 cards and systems on time 
with the applications and assistance to suppotf them! 

Reliable? You bet! 

Every product is operared for a full 7 day burn in 
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Support? Count on it! 

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standatd DOS, CP/M ot Pascal applications. Call the 
SVA Hotline fot a list of application softwate that tuns 
on the MEGABYTES systems. 

Look to SVA for a growing line of Apple Memory 
System products . . . SVA means business. 




DISK 2+2 

8" Floppy Disk Controller 

Single density - Single/double sided 

Twice rhe Byte 



Intelligent disk controller doubles the disk 
storage capacity of rhe Apple. Compatible 
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Operates concurrently with mini disks. Load 
and run other CP/M and Pascal disks or 
transport/copy doro disks of any computer 
using rhe IBM 3740 format. 




ZVX4 MEGADYTER 

8" Floppy disk controller 

Dual density - Single/double sided 

Four Times rhe Byte 



All rhe fearuresofDisk2+2plus IBM Sysrem 
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asm 



APP-L-CACHE 

256k RAM Memory Cord 

Memory wirh disk emuloror ROM 

Mini disk cosr - Hard disk performance 



Operare as a standard 16k memory cord 
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or Pascal applicarions ond warch rhe brain 
power of rhe Apple grow. Combine wirh on 
SVA 8" floppy sysrem for doro rransporrobiliry 
and backup. 



MEGADYTER SOFTWARE 

Dedicated to standards and supporr 

Applicarion Horline ossisronce: 

(714)452-0101 

Doro Tronsporrer: Move doro 
berween computers wirh; DOS ro 
IBM, CP/M ro IBM. CP/M ro DEC. 
Disk Copier : Copy any 8" IBM 
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Circle 386 on inquiry card. 



General Business: Supporr for; The 
Apple Conrroller*. Accounring II 
Plus*, Peochrree*, BPI* ond orhers. 
Word processing: Mogic Wand*. 
Apple wrirer* Word Sror*. Pascal 
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SORRENTO VALLEY ASSOCIATES 

11722 Sorrenro Valley Road 
Son Diego, CA 92121 
(714) 452-0101 



BYTE December 1981 



297 



System Notes 



I was playing with a program that moved boxes around 
on the screen when I got the idea for the Left/Right game. 

Writing the program was fairly simple; most of my 
time went into the display design, the choice of various 
parameters, and, of course, the complications. 

As I added complications for the player, the program 
grew more complicated — to the point where I rewrote it 
entirely for this article. Writing the program for the com- 
plicated case and then simplifying for low scores is actu- 
ally easier. Table 1 shows the complications built into the 
program. As you can see, there is a symmetry to the com- 
plications, with a new one added roughly every third 
play. The symmetry would be more complete if the bars 
changed color only when the score equaled 6 modulo 9; 
but that did not produce color changes often enough to 
satisfy my intuitive sense of play. 

Choosing colors to use was a project in itself. As long 
as the score is less than 27, the colors come in reasonable 
pairs (red/blue, green/orange, yellow/purple). After 27, 
not only is a new pair of colors added (pink/white), but 
the old colors can appear in new and harder pairs. 

Listing 1 is the Apple II Integer BASIC program of 
Left/Right. Lines 1000 to 1730 initialize a few variables 
and print the instructions, while line 1900 begins the pro- 
gram proper. From 1900 to 1997, I set the score to zero, 



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determine which switch is in the player's left hand, and 
clear the screen. 

Lines 2000 to 2114 set up the general (complicated) 
case, choosing which bar the box will match, where the 
box will be, what quarters of the background will be 
grey, and what colors will be used. Lines 2120 to 2330 
simplify the situation for low scorers like me. The 
simplifications are made according to table 1 (page 278.) 

From line 2340 to 2550, 1 draw the screen: background, 
bars, and box. Then, from line 2560 to the end, I wait for 
the player to push either switch, determine whether it is 
right or wrong, and add one to the score or end the game. 

Since the logic gets confusing at the program's end, I 
have provided a flowchart of the program in figure 1, 
with an emphasis on the last lines. Other than at the end, 
the program is basically two nested loops; the outer loop 
begins at line 1900 with each new game, and the inner 
loop starts at line 2000 for each play. 

Table 2 is a truth table for the logic behind the expres- 
sions in lines 2680 and 2710, which test for correctness of 
player response. For those of you implementing this game 
on a machine other than an Apple, I have summarized 
the Apple graphic and other special commands in table 3. 

Additions 

Several possible changes suggest themselves. You can 
change the timing, eliminate it entirely, or time each 
point. You can increase the number of colors or divide 
the screen up into more areas. You can use shapes other 
than a box, or letters and words, with or without adding 
another level to the logic as I just discussed. Lacking a 
computer with color capability, you can base the game 
on shapes rather than colored bars. 

A challenging modification for the player and the pro- 
grammer would have the box move. To press the appro- 
priate switch, a player would have to remember where 
the box started. 

To increase the time limit for each player, modify line 
1120. To eliminate the timing entirely, delete line 2630. 
To time each point, move line 1997 to 2570. 

The number of colors may be increased by changing the 
dimension of C in line 1010 and increasing the arguments 
to the RND function in lines 2114 and 2150. Note that 
line 2150 is deliberately constructed to use fewer colors 
than are available. Also, since lines 2114 and 2150 choose 
the color pair, the maximum value allowed for LC is one 
less than the number of array elements. A particularly 
fiendish modification would use the various shades of 
blue which are available on the Apple as possible ele- 
ments of color pairs. The box is drawn in lines 2510 to 
2550; to change its shape, modify this code. 

Summary 

A fun game, it has been a party favorite. It's a great 
demonstration. Watching an experienced player (like my 
wife) run up a high score is just part of the fun. ■ 



298 December 1981 © BYTE Publications Inc 



Circle 330 on Inquiry card. 



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If you have an Apple, TRS-80, Zenith, North Star or 
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Call Omni toll-free today. Get premium disks. Twice 
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(800) 343-7620 In Mass. (617) 799-0197 

Dealer inquiries invited. 

Software Houses: We also offer duplicating and 

formatting services. 



$21.00-Five pack 

(Equivalent to lO single-sided disks) 

$4QOO-Ten pack 

(Equivalent to 20 single-sided disks) 

Free 

Protective plastic 
stoiage case with each 
lO pack ordered by 
12/25/81 

Order toll-free (800) 3437620. 
In Mass. (617)799-0197. 

Circle 315 on inquiry card. 




Send the following Flip/Floppy disks. 

I understand they have a full 90 day money-back 
guarantee if I'm not completely satisfied. 

System & model # 

Five packs @ $21.00 S 

Ten packs @ $40.00 ' $ 

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BYTE December 1981 



299 



Atari is hot Ste 

The ATARI® 800™ Computer is getting rave reviews. High OPTIONAL ACCESSORIES CONT. PRICE 

resolution color graphics and English characters; high quality . TAR|@ fi „„ TU Thprm _, Printpr . , dq m 

sound; and sleek, modular appearance have made the 800 a ATARI 8 ^ ' hermal Prmter s ^ w 

"must have" for many computer users. Expandable memory, ATARI® 825™ 80-column Dot Matrix Impact Printer . S 625.00 

advanced peripheral components, and comprehensive ATARI® 830™ Acoustic Modem $ 159.00 

software library make ATARI a really hot deal, whether your ATARI® 850™ Interface Module $ 159.00 

application is business, professional or personal. ATAR|@ Pa(Jd|e (CX30 . 04) or Joystjck (CX40 . 04) $ -,795 

SPECIAL OFFER - ASAP makes the ATARI® 800™ the hottest Li ht Pen (CX . 70) , 6495 

deal in town by offering 16K bytes of additional RAM . . . FREEI 

You get 32K for the price of 16K. Complete Software Library includes these popular units: 

So don't get caught out in the cold. Call ASAP today. Star Raiders $ 36.00 

Space Invaders $ 15.95 

OPTIONAL ACCESSORIES PRICE Assembler Editor $ 42.00 

ATARI® 410™ Program Recorder $ 60.00 Missile Command $ 34.00 

ATARI® 810™ Disk Drive $ 455.00 Asteroids $ 34.00 

ATARI® 820™ 40-column Dot Matrix Impact Printer. . . $ 279.00 word Processor $ 119.00 



Well f f drive" you wild 

with our variety oi 
qualify disk drives. 



ASAP carries only the highest quality floppy disk drives, to 
provide you with years of trouble-free service and superior 
performance. 

Data Trak™ 5 (ANSI 5W* compatibility) Call for price 

Data Trak™8(IBM compatibility) Call for price 

Model 801 (standard floppy) $425.00 

Model 850 $640.00 

Dual Disk Drive Cabinet $225.00 

ASAP also provides a full line of high reliability disk drive 
subsystems*. 

HDC8/1-HD — Cabinet with (1) Priam 10 megabyte hard disk 

drive with Microbyte Controller installed Call for price 

HDC8/1F+1HD — Cabinet with (1) Qume DT-8 double-sided 
double-density drive, and (1) Priam 10 megabyte 
hard disk drive with Microbyte Controller 

installed Call for price 

CAB8H — Dual cabinet for 8" floppy disk drives 

(horizontal mounting) $ 225.00 

CAB8V — Cabinet for 8" floppy disk drives 

(vertical mounting) $ 225.00 

CAB8H/V+1S — Dual cabinet with (1) Shugart SA801R 
installed (horizontal or vertical mounting) $ 750.00 



CAB8H/V+ZS — Dual cabinet with (2) Shugart SA801R's 

installed (horizontal or vertical mounting) $1150.00 

CAB8H/V+1Q — Dual cabinet with (1) Qume® DT-8 
double-sided double-density drive installed 

(horizontal or vertical mounting) $ 830.00 

CABH/V+20 - Dual cabinet with (2) Qume® DT-8's 
double-sided double-density drive installed 

(horizontal or vertical mounting) $1350.00 

X5 — Cabinet for desk top mainframe 

(small power supply) $ 200.00 

800D — Cabinet for desk top mainframe 

(standard power supply) $ 255.00 

*AII cabinets come complete with power supply, fan 
and internal cables. 



;is;iii 

computer ■ 
products, inc. 



Circle 33 on Inquiry card. 



SDSystems/S-1 00 Board 



SYSTEMS WITH SPICE from 
CALIFORNIA COMPUTER SYSTEMS 

FOR APPLE \r USERS 

Synchronous Serial Interface 

Part Number 7712A Price: S149.00 

Programmable Timer 

Part Number 7440A Price: S 95.00 

Asynchronous Serial Interlace 

Part Number 7710A Price: S139.0O 

Calendar/Clock Module 

Part Number 7424 Price: S 99.00 

V .. Digit BCD A-to-D Converter 

Part Number 7470A Price: S 95.00 

12K ROM/PRDM Module 

Part Number 7114A Price: S 85.00 

Parallel Interlace 

Part Number 7720A Price: S125.00 

Arithmetic Processor 

Part Number 7811 A Price: $349.00 

Centronics Printer Interface 

Part Number 7728A Price: S125.00 



FOR S-100 USERS 

32K Static RAM Board 

Part Number 2032C Price: S610.00 

16K Static RAM Board 

Part Number 2116C Price: $290.00 

64K Dynamic RAM Board 

Part Number 2065C •. Price: S550.00 

Z-80A CPU Board 

Part Number 2810A Price: $265.00 

Floppy Disk Controller 

Part Number 2422A Price: $365.00 

CP/M™ Version 2.2 Free With Purchase 
S-100 Mainframe 

Part Number 2200A Price: $475.00 

2201A (220VAC) $475.00 

S-100 Motherboard 

Part Number 2501A Price: S150.00 

4-Port Serial I/O Interface 

Part Number 2710A Price: $245.00 

2-Serlal. 2-Parallel I/O Board 

Part Number 2718A Price: S275.00 

4-Port Parallel I/O Board 

Part Number 2720A Price: $195.00 



DISKETTES from ASAP 




8" DISKETTES 










Part# 


Sides/Density Sectoring 


Price 








D-0506 


1/Single Soft 


10/S45.00 




VERBATIM 




D-0605 


2/Double Sofl 


10/565.00 




5'/." DISKETTES 






SCOTCH 3M 




Pari # 


Sectoring 


Price 




5V." DISKETTES 




MD525-01 


Soft 


10/S27.50 


Parts 


Sides/Densily Sectoring 


Price 


MD525-10 


Hard 10 


10/S29.50 


744-0 


1/Single Sofl 


10/S33.00 


MD525-16 


Hard 16 


10/S29 50 


744-10 


1/Single Hard 10 


10/S33.00 




8" DISKETTES 




744-16 


1/Single Hard 16 


10/S33.00 


FD32-1000 


Hard 


10/535.00 


745-0 


2/Double Soft 


10/S59.00 


FD34-1000 


Soft 


10/S3500 


745-10 


2/Double Hard 10 


10/S59.00 




MEMOREX 

5%" DISKETTES 




745-16 


2/Double Hard 16 

MAXELL 

5V«" DISKETTES 


10/S59.00 


Part* 


Sides/Density Sectoring 


Price 








MEM 3401 


1/Single Soft 


10/S25 00 


Parts 


Sides/Densily Sectoring 


Price 


MEM 3403 


1/Single Hard 10 


10/S25.00 


MD1 


1/Single Soft 


10/S39.00 


MEM 3405 


1 /Single Hard 16 


10/S25.00 


MD2D 


2/Double Soft 


1O/S6500 








MH1 


1/Single Hard 16 


10/S39.00 




8" DISKETTES 




MH2D 


2/Double Hard 16 


10/565.00 


Parts 


Sides/Density Sectoring 


Price 




8" DISKETTES 




MEM 3060 
MEM 3101 


1/Single Soft 
2/Single Soft 


10/S35.00 
10/S45.00 


Parts 


Sides/Density Sectoring 


Price 


MEM 3090 


1 /Double Soft 


10/S45.00 


FD1-128 


1/Single Soft 


10/S45.00 


MEM 3102 


2/Double Soft 


10/S55.00 


FH1-32 


1/Single Soft 32 


10/S45.00 




OYSAN 




FD2-XD 


2/Double Soft 


10/565.00 




5V." DISKETTES 






SRW 




Part # 


Sides/Densily Sectoring 


Price 




MEDIA STORAGE CASES 




D-0130 


1/Single Soft 


10/S45.00 


Parts 


Size 


Price 


0-0226 


1 /Double Soft 


10/S46.00 


SRW-5 


5W 


$2.50 ea. 


D-0235 


2/Double Soft 


10/S55.00 


SRW-8 


8" 


S3.25 ea 


MICROBYTE Z-80A/ 




MICROBYTE 4-PORT 




I/O CPU BOARD 




I/O BOARD 





• A complete single board ZBOA CPU with 
serial/parallel interface 

• Fully compatible with the proposed IEEE S- 
100 Bus Standard 

• Z80A CPU (4MHz version of the Z80) 

$329.00 Assemb|ed & Tested 

Oplional Monitor Program S30.00 



MICROBYTE 64K DYNAMIC 
RAM BOARD 

• Fully S-100 bus compatible 

• 64K x 8 bit dynamic RAM 

• Low power: 
•8VDC @ 700 mA 
•16VDC @ 100 mA 
-16VDC @ 25 mA 

• Built-in capacity with LED indicator and 
vector interrupt 



• Quad RS-232C serial ports. One 20 mA 
current loop port 

• Fully IEEE S-100 Bus compatible 

• Asynchronous Communications with 
Z80A-DART(TM) or synchronous commu- 
nications with Z80A-SI0/0(TM) 

• Full set of modem control signals, 
including Rl (Ring Indicator) 

• Easily configurable to any type of terminal 
interface 

2265.00 Assembled 8. Tested 
Cables Available (Optional) 

MICROBYTE FLOPPY DISK 
CONTROLLER 

• DMA to within 16 Mbyte of memory 

• State-of-the-art NEC765 LSI Controller- 

• IEEE S-100 compatible 

• DMA arbitration allows use of multiple 
boards within a system 



EXPANDORAM 


16K 


$240.00 


2 MHz DYNAMIC 


32K 


$258.00 


RAM BOARD 


48K 


$276.00 


KITS 


64K 


$294.00 


EXPANDORAM II 


16K 


$250.00 


4 MHz DYNAMIC 


32K 


$268.00 


RAM BOARD 


48K 


$286.00 


KITS 


64K 


S3O4.0O 



SBC-100 KIT 2.5 MHz/Z80 CPU with Serial I/O 
Ports & SBC 100 Monitor of your choice at 

no charge $299.00 

SBC-200 KIT 4 MHZ/Z80A CPU with Serial & 
Parallel I/O Ports & SBC 200 Monitor of your 

choice at no charge $325.00 

VERSAFLDPPY I KIT Disk Controller for 5V." or 8" 
Drives. Single or Double Sided/Single or Double 

Density. S-100 Compatible $250.00 

VERSAFLDPPY II KIT Disk Controller for 5V<" or 8" 
Drives, Single or Double Sided/Single or Double 

Density, S-100 Compatible $300.00 

PROM 100 KIT S-100/EPROM PROGRAMMER for 

2708, 2716, 2732 & (Tl) 2516 $190.00 

ALL BOARDS ARE AVAILABLE ASSEMBLED & 
TESTED. CALL FOR PRICES. 

Printers 

Okidata Dot Matrix Printer 

82A — 80 column printer 

Throughput @ 80 characters per line: 76 lines 

per minute 

Print Speed: 120 CPS 

83A — 136 column printer 

Throughput @ 136 characters per line: 47 lines 

per minute 

Print Speed: 120 CPS 

Centronics & RS232C interfaces standard on both 

models 

The Epson MX-80 

80 Column Dot Matrix Printer 
PRINTING CHARACTERISTICS 

Character set: full 90-character ASCII with 

descenders. 

Graphics characters: 64 block characters 

INTERFACES 

Standard: Centronics-style 8-bit parallel 

Optional: Apple, TRS-80, RS 232 

NEW 

MX80 FT/Friction Feed 

MX-100/132 Column 

CALL FOR PRICE & DELIVERY 



SEP 



AEI-1 W/Cable S69.95 

• Standard Interface 

• Compatible with Epson & Okidata printers 

• On-board firmware (2708) 

• Optional cables: $25.00 

• AEC-2/Atari to Epson printer 

• TREC-2/TRS-80 to Epson/Okidata printer 

• RSC-1/RS232 (male to male) 

Serial Interlace SEI-1 $55.00 

• Asynchronous 300. 1200. 2400 or 9600 BPS 

• Compatible with Epson printers 

• 75 to 9600 BPS 

Manufacturer/Model S Price 

Anacom-150 $ 995.00 

Anadex-9501 $1295.00 

Diablo-630R0 $2300.00 

C.ltohStarwriter 45 $1925.00 

Texas lnstruments-810 $1650.00 

Modems 



Manufacturer Model S 

Novation CAT 

Novation d-CAT 

Novation Auto-Cat 



Price 
$ 149.00 
S 160.00 
$ 229.00 



Lexicon 


Lex-11 


$ 139.00 


Livermore 


UV-Star20M 


$ 149.00 


UDS 


UDS 103 


$ 189.00 


UDS 


UDS 202 


$295.00 


Monitors 






Manufacturer 


Model « 


Price 


Amdek 


100/12" B&W 


$ 139.00 


Amdek 


100-80 


$ 169.00 


Amdek 


10DG/12" Grn. 


S 169.00 


Amdek 


Color-1 13" 


$ 375.00 


APF 


TVM-10/10" B&W 


$ 149.00 


Hitachi 


VM 910/9" B&W 


$ 210.00 


Hitachi 


VM 129/12" B&W 


S 340.00 


Sanyo 


DM 5012/12" B&W 


$ 270.00 


Sanyo 


DM 5112ex/12" Grn. 


S 290.00 


Sanyo 


DM C6013/13" Color 


S 475.00 


Zenith 


ZVM-121/12"Grn. 


S 129.00 


Terminals 






Manufacturer 


Model « 


Price 


Ampex 


Dialogue 80 


S 899.00 


Soroc 


10120 


$ 750.00 


Soroc 


1Q140 


S1 250.00 


Teievideo 


TVI910 


5 650.00 


Televideo 


TVI 912C 


$ 725.00 


Teievideo 


TVI950C 


S 950.00 


Components 




4116s (200 nS) 




Apple, TRS-80, 


Heath 


. . .8/S18.00 


16-49 




. $2.15 each 


50-99 




. S2.05 each 


100 up 




.$1.95 each 


21I4L-2/200 nS 




Low-Power 1K 


x 4 Static RAM 




1-16 $2.95 each 




17-49 $2.85 each 




50-99 $2.75 each 




100 up $2.65 each 




Components 




74LS240... S1.25 each 74LS373... 


$1.25 each 


74LS241... $1.10 each 74LS374 . . . 


$1.25 each 


74LS244... $1.25 each 8T245 


$1.50 each 


2708/450 nS 




1K x 8 EPROM 


$3.50 each 


or 8/$26.00 


2716/5 Volt 




2K x 8 EPROM 




. $5.50 each 


Support Chips 




8080A-CPU.... 


S 2.50 Z80A-SI0 . . 


. .. $22.00 


Z80A-CPU ... 


S 8.95 8255AC5 . . 


. . . $ 6.95 


Z80A-CTC ... 


S 8.95 8257AC5 . . 


... $15.00 


Z80A-DART . . 


$13.95 




Regulators 






320T5. 


. $ .80 320T12 .... 


. . . . $ .80 


340T5 


. S .70 340T12 .... 


... $ .75 


Connectors 








1-9 10-24 


25 up 


DB25P 


$2.25 $2.15 


$2.00 


DB25S 


$3.25 $3.10 


S2.90 


DB25C 


$ .95 S .85 


$ .75 



100 Pin IMSAI 

Gold/S-100 Soldertail Connectors 
S2.60 each or 10/S2.40 each 

Capacitors 

.1 @>12 Volt Ceramic 8C each or 100/S7.00 

DIP Sockets — Low Profile 
Tin Soldertail 



Description 
14 pin tin st 
16 pin tin st 
18 pin tin st 

20 pin tin st 
24 pin tin st 
28 pin tin st 
40 pin tin st 



1-9 

$ .15 

$ .16 



10-49 50-99 

$ .13 $ .12 



$ .14 



S .19 $ .18 
$ .25 S .23 



$ .26 
$ .32 
$ .42 



$ .24 
$ .30 

$ .40 



$ .13 
S .16 
S .21 
$ .22 
$ .29 
$ .38 



100 up 

$ .11 
$ .12 
$ .14 
$ .20 
$ .20 
$ .27 
$ .34 



ASAP offers a 30-day buyer protection policy: full money-back guarantee if not 
totally satisfied. 

Ordering Information: Name, address, phone, ship by: UPS or Mail. Shipping 
charge: add $2.50 up to 1 lb. for UPS blue; add $1.50 for U.S. Mail (U.S. only) 
($25.00 minimum order). Call for larger shipments. 
Terms: We accept cash, check, money orders, Visa & Master Charge (U.S. 
Funds only). Tax: 6% Calif. Res., COD's and terms available on approval (school 
PO's accepted). 



$499.00 Assembled & Tested $329.00 Assembled & Tested 



asaii 

computer ■ 
products, inc. 

1 198 E. Willow St., Signal Hill, CA 90806 



Toll free outside California: 

(800) 421-7701 

Inside California: 

(213) 595-6431 
(714)891-2663 



Circle 33 on inquiry card. 



•••••••••••••••••••••••••^••••••* 

1 






e 



** 



CO** 



¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 
¥ 

¥ 

¥ 

¥ 

302 December 1981 © BYTE Publication* Inc 



Prizes Prizes Prizes 

First prize: $ 500 
Second prize: $250 

Third, fourth, and fifth prizes: A bound copy of BYTE Volume 1 , which covers 

September 1975 through December 1976 

Sixth, seventh, and eighth prizes: Publication of your game in BYTE 

All prize-winning programs will be published In BYTE 



Admit it. When you were desperately trying to justify the purchase of your personal toy . . . uh . . . com- 
puter, you had absolutely NO idea that it could be used for endless hours of game playing. Instead, you 
were dazzled by the possibilities for using it in applications that are on the very frontier of computer 
engineering. Your sights were set daringly high: "Let's see, balancing my checkbook, uh . . . phone list 
(there was something else . . . ) turn on the lights when I'm away on business (but what about mowing 
the grass?), uh . . . (oh, yes) and a computerized phone list .... Uh, there was something else, but I forget 
what it was . . . . " 

Two years later, you're still balancing your checkbook by hand and you don't have that computerized 
phone list just yet. But you do have 35 disks of something in your software library — and they aren't multiple 
linear regression analysis packages, either. 

It's okay. Your secret is safe with us. We like games, too. In fact, we're looking for games to publish. We 
know that the countless hours you spend programming is for serious stuff, but if you know anybody who's 
into games, you might mention we're running a contest. 



********************************* 



The Format 



The Gaines • • 



' All games should be presented in article form for possible 
publication in BYTE. (Send a stamped, self-addressed, legal- 
size envelope for a copy of our author guide.) Submit your 
game in the magnetic format listed below, along with 
whatever documentation is necessary, a clear listing, and 
an introductory narrative telling us about the game and 
how it works. Floppy disks should be sent sandwiched be- 
tween two pieces of cardboard. Be sure to keep a copy of 
any software you send us [just in case it does get damaged 
in transit). 



The Computers 



Prepare your game for one of the following computers, in 
the format indicated. (We apologize if your computer is not 
on this list, but we are limited to those to which we have ac- 
cess.) Games must be submitted in the appropriate form. 



Apple II, Atari 800, Commodore 
PET/CBM, IBM Personal Com- 
puter. Radio Shack TRS-80 
Models I or III 

Commodore VIC, Radio Shack 
TRS-80 Color Computer 

Radio Shack TRS-80 Model II 

CP/M with "plain vanilla" ter- 
minal (ie: no special features) 



5-inch disk only 

cassette tape 

TRSDOS 8-inch disk 
standard 8-inch disk 



What kind of games are we looking for? Graphic arcade- 
style games (of course); text-only simulations, role-playing 
games, and adventures; strategy games; abstract games; ac- 
tion games; historical games. Anything that's funl And a 
game needn't occupy 48 K bytes of memory to be fun— it's 
the concept that countsl (For an example of a simple game 
that's fun, look at "The Game of Left/Right" for the Apple II 
on page 278 of this issue.) 

Use your creativity to devise something new, rather than 
implementing something that already exists. We aren't in- 
terested in implementations of existing board or video 
games— we want original games onlyl 

We'd be very interested in seeing a two-computer game. 
In it, two people run the same game on two computers, 
which are connected by an RS-232C link (or, for the Apple, 
possibly a 3-bit duplex connection through the game port). 
For an example of what's possible using two computers, 
see the review of Commbat on page 100 of this issue. 



The Deadline •••••• 



Entries must be sent to: 

BYTE Game Contest 

POB 372 
Hancock NH 03449 

and must be postmarked by March 31, 1982. The results 
will be published in the August 1 982 issue of BYTE. 



* 
* 
* 

* 

* 

* 
* 

* 
* 
* 
* 



The Fine Print ••••••••••••••••• 



•This contest will be judged by the BYTE editorial staff. The games will be evaluated for their payability. The judges' 
decision is final. 

•Game submissions cannot be returned unless they are accompanied by a return envelope with sufficient postage on 
it. 

•This contest is open to anyone except employees or immediate family of McGraw-Hill and its subsidiaries. Void 
where prohibited by law. 

•Prize winners will exchange first serial rights (ie: the right for BYTE to publish their article first). In all cases, the author 
retains all commercial rights to the software written, and BYTE readers cannot distribute and/or sell the software 
without the author's permission. All eight prize winners will receive the standard payment for a BYTE article (at S50 per 
published magazine page). 

•Only one entry is permitted per contestant. 

•To repeat a rule stated earlier, cassette tapes will be accepted only for the Commodore ViC and the Radio Shack 
TRS-80 Color Computers. All other entries must be in the floppy-disk format specified above. 



* 
* 
* 

* 
* 
* 
* 
* 
+ 
* 

* 



The Bottom Line 



We think this contest is arranged so that anybody with a good idea has a chance to win. We won't be dazzled by J^- 

fantastic graphics alone, but we will be influenced by how enjoyable a game is. We look forward to seeing your best ef- yi 

fort and hope you'll have fun in the process. 

Ar******************************** 



December 1981 © BYTE Publications Inc 303 



Software Review 



Pascal-80 



Rowland Archer 

Flint Ridge Apartment 59 

Hillsborough NC 27278 



Even though several versions of Pascal have been 
available for the TRS-80 Model I computer for some time 
now, none of them quite succeeds in terms of com- 
pleteness and compatibility with the TRS-80 system. 

For example, Radio Shack's own Tiny Pascal is educa- 
tional and inexpensive, but it is an extremely limited sub- 
set of Pascal. It provides integer data types, one-dimen- 
sional arrays, and Pascal control structures, but none of 
the type-definition facilities that make Pascal a unique 
language. It also provides no means of storing or retriev- 
ing data from tape or disk, eliminating it as a contender 
for most serious uses. 

FMG Corporation's version of UCSD (University of 
California, San Diego) Pascal for the TRS-80 is more 
complete, but it suffers from a force fit to the Model I ma- 
chine. FMG told me it is essentially a vehicle for teaching 
Pascal due to the small user-program space available (ac- 
cording to FMG, about 250 lines). 

Having witnessed several partially successful attempts 
to put a Pascal system on the TRS-80, I began to think it 
just wasn't practical. After all, the Apple II version of 
UCSD Pascal requires a memory expansion to 64 K bytes 
and a modification to the disk operating system to sup- 
port higher-density disk storage. Knowledgeable people 
claimed that the TRS-80 Model I, with its 48 K bytes of 
memory and single-density floppy-disk system, was not 
big enough to support Pascal. 

It was thus with considerable excitement that I read 
TSE-Hardside's advertisement for Pascal-80 by Phelps 
Gates. I have used Mr Gates's excellent APL interpreter 
(also distributed by TSE-Hardside) for nearly a year, and 
it is notable for its completeness, compactness, and 
freedom from bugs. APL is another example of a lan- 
guage that many experts claimed could never be put on a 
TRS-80. If anyone could devise a good Pascal system for 
the TRS-80, it was Phelps Gates. I am happy to report he 
has done just that. 

It is worth saying a few words about Gates himself, as 
he has an intriguing combination of professional in- 
terests. Churning out interpreters and compilers is only a 



sideline for him. In real life, he is an associate professor at 
the University of North Carolina— in the classics depart- 
ment! His choice of avocation becomes less surprising 
when you learn he specializes in linguistics, which helps 
explain his expertise in computer languages. That he, 
rather than a computer professional, has put together 
good, complete versions of APL and Pascal for the 
TRS-80 should be a lesson to all of us. The supposed ex- 
perts probably never tried because they "knew" it 
couldn't be done. 

System Overview 

Pascal-80 is a stand-alone system written in Z80 ma- 
chine code and distributed on a TRSDOS disk (Model I 
or III format). The original disk may be copied with the 
TRSDOS BACKUP utility. I have run Pascal-80 under 
NEWDOS 40 to make use of my 40-track drives. So far, I 
have had no problems doing so. However, I have not 
been able to get Pascal-80 to run under NEWDOS 80 or 
LDOS. 



Af a Clanrp 


Name 


Format 


Pascal-80 


5-inch floppy disk, TRS-80 




Model I or III TRSDOS 


Type 


format 


TRS-80 Pascal compiler 






Computer 


Author 


TRS-80 Model I or III with 


Phelps Gates 


at least 32 K bytes of 




memory; at least one disk 


Distributor 


drive 


TSE-Hardside 




6 South St 


Documentation 


Milford NH 03055 


14-page instruction booklet 


(800) 258-1790 






Audience 


Price 


Programmers in need of a 


Disk plus instruction 


Pascal compiler for the 


booklet, $99.95 


TRS-80 Model I or III 



304 December 1981 © BYTE Publications Inc 



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To start Pascal-80, you simply type in the program 
name under TRSDOS READY. The program starts by 
displaying the menu; table 1 lists the options available. 

The entire system resides in memory at once — editor, 
compiler, and p-code interpreter. This makes Pascal-80 
convenient and interactive, much like Disk BASIC. You 
can move quickly between editing, compiling, and run- 
ning a program without the need to save intermediate 
forms of the program on disk. The major difference be- 



EDIT the program in memory or create a new program from 

scratch. 

KILL (erase) the program currently in memory. 

SAVE the program in memory to a named disk file. 

LOAD a previously saved program from disk to memory. 

APPEND from a disk file to the program in memory. 

COMPILE the program in memory, producing p-code that can be 
run or saved in a disk file. The program text remains in 
memory. 

WRITE the p-code produced by the compiler into a named 
disk file. 

EXECUTE a p-code file directly from disk, overwriting the com- 
piler to gain extra memory for run-time. 

RUN the program in memory, compiling it first if necessary. 

QUIT Pascal-80 and return to the TRSDOS command inter- 

preter. 

Table 1: Options available with the Pascal-80 monitor. 



tween running Disk BASIC and Pascal-80 is that with 
Pascal-80 you must compile a program before running it. 
(And there is no "immediate mode" allowing eva\ua\.\on 
of instructions like PRINT 3/7 without embedding them 
inside a program. I know of no Pascal system that sup- 
ports such a mode.) 

For those of you unfamiliar with compilers, p-code, 
and run-time packages, here's a little background. The 
compiler takes your original source code, created using 
an editor, and translates it into an intermediate form 
called p-code. The p-code is then interpreted into ma- 
chine language by the run-time package or p-code inter- 
preter. For further information on this process, see the 
three-part article, "A 'Tiny' Pascal Compiler," starting in 
the September 1978 BYTE. 

The compiler is very fast. TSE-Hardside claims that it 
converts 1000 lines of Pascal code per minute to ex- 
ecutable p-code; my timings indicate this is very conser- 
vative. I get closer to 2000 lines per minute when the 
source is listed to the screen as it is compiled. When I turn 
off the source-listing option, I obtain compilation speeds 
of around 3000 lines per minute. These figures are very 
impressive; for comparison, Tiny Pascal, which handles 
only a small subset of the language, compiles about 100 
lines per minute. 

Naturally, there is a trade-off for the convenience and 
speed of having everything reside in memory at once. 
You are limited to compiling programs that can fit in 
memory all at one time. However, Pascal-80 conserves 



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306 December 1981 © BYTE Publications Inc 



Circle 349 on inquiry card. 



memory by using a space-compression technique: consec- 
utive blanks are counted and stored as a single byte with 
the high-order bit turned on. 

This technique provides ample space for user pro- 
grams. In a TRS-80 with 48 K bytes of memory, there are 
about 23,600 bytes for user programs. With strings of 
blanks compressed to a single byte, the average Pascal-80 
program line is about 20 bytes long. There is space for 
1180 such lines of code. The actual number depends on 
the style of the individual programmer. The estimate of 
20 bytes per line is conservative as most Pascal programs 
contain many lines with nothing but BEGIN or END on 
them. 

Systems that provide a separate editor, compiler, and 
run-time module require only components actually in use 
to be resident in memory, providing more space for user 
programs. On the other hand, however, such systems are 
more cumbersome to use because you must access the 
disk drives frequently to load each component of the sys- 
tem as it is needed, usually saving the output of each 
phase in a separate disk file. 

I like the interactive quality of Pascal-80 and wouldn't 
want to sacrifice that for the extra capacity of a system 
that uses a separate editor, compiler, and run-time mod- 
ule. However, there are times when extra program space 
comes in handy, and a simple enhancement to the com- 
piler would provide some: a command inserted into a 
Pascal source program to direct the compiler to start 



compiling source code from a disk file. This compiler 
command is usually called an INCLUDE facility. It 
allows the compilation of programs even though the 
source code is larger than memory. It also allows you to 
create a library of useful Pascal routines that can be IN- 
CLUDEd in programs as needed, rather than being typed 
or chained from disk using an editor. 

General Procedure for Use 

Here is a summary of the steps involved in creating, 
compiling, and running a Pascal-80 program: 

1. Type PASCAL from the TRSDOS READY prompt to 
load the Pascal system and enter the monitor mode. 
The options available are shown in table 1. 

2. Type E to enter the editor, which allows you to type in 
the source text for your Pascal program. When you 
finish typing in the text, exit from the editor by typing 
Break M, which returns you to the monitor mode. 

3. Type C to compile your program. The starting time of 
the compilation appears on your screen followed by 
the text of the program itself as it is compiled, unless 
you have selected the NOLIST option. If your pro- 
gram contains an error that prevents it from compiling 
properly, compilation is halted immediately. When 
you type E to reenter the editor to correct the mistake, 
the editor's cursor is positioned at the point of the 
error, all set for you to correct it. This is a nice touch. 



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December 1981 © BYTE Publications lnc 307 



and the procedures NEW and 



variables and the pro- 



13 Variant records. 

[3 The WITH statement. 

[3 Pointer variables 
DISPOSE. 

(3 File window or "buffer' 
cedures PUT and GET. 

[3 The data attribute PACKED is not needed, since all 
structures are already packed on byte boundaries. This 
means that Pascal-80 is automatically as space-efficient as 
possible in storing data, without the need for PACKing and 
UNPACKing data. 

13 The procedure PAGE is not included. You can use 
WRITE(LP,CHR(12)) to send an ASCII form-feed character 
to the line printer. 

I3 Structures of FILEs, such as ARRAY of FILE, are not 
permitted. 

K/ Procedures and functions may not be passed as pa- 
rameters to other procedures or functions. 

[3 The total size of an expression passed as a value 
parameter may not exceed 510 bytes (but this is not a limita- 
tion for VAR parameters). 

[3 Sets may have no more than 256 members. If the 
elements of a set are numeric, they must be in the range of 
to 255. 

Table 2: Standard Pascal features that are not implemented 
in Pascal-80. 



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4. Once you have compiled your program with no 
errors, type R to run it. If you find an error during 
your program's execution, go back into the editor 
from the monitor mode, correct the error, and start the 
compile-and-run cycle again. 

5. From the monitor mode, you can perform various 
kinds of program storage and retrieval: save the cur- 
rent source program, save the current compiled pro- 
gram, load a source program, or load and execute a 
previously compiled program from disk. This latter 
option has a special benefit — it gives you about 10 K 
extra bytes of free memory for use at run-time. Since 
the program has already been compiled, the compiler 
portion of Pascal is not needed. So when you choose 
this option, your program overwrites the Pascal com- 
piler, giving you the extra memory. 

Editor 

The Pascal-80 system includes a simple full-screen 
editor. It allows you to move a blinking cursor around on 
the screen and type over any text to change it. Changes 
that appear on the screen are not actually made to the 
text until you press the Enter key with the cursor posi- 
tioned on that line. This is confusing at first because it is 
easy to make changes to one line and then use the up- 
arrow or down-arrow key to move to another line, with- 
out pressing Enter to make the changes take effect. 

Another bothersome aspect of this editor is the lack of 
character delete and insert commands. This requires you 
to retype most of a line that needs something inserted or 
deleted. There is a line insertion and deletion command, 
however. There is also a command to scroll backward or 
forward one page at a time in the text buffer. 

It is handy to have this editor available during program 
debugging; it allows you to move quickly between edit- 
ing, compiling, and running the program being tested. In 
my opinion, however, it is just too simple to serve as the 
primary editor for creation and heavy maintenance of 
large source files. 

I have a suggestion to remedy this limitation: use a full- 
featured editor such as Radio Shack's Scripsit for pro- 
gram creation and major editing; use the Pascal-80 editor 
solely for interactive development. You can't do this with 
the present release of Pascal-80 because the source code is 
saved on disk in a compressed format that cannot be read 
in by a general-purpose editor. However, it shouldn't be 
too difficult for author Gates to add an ASCII (American 
Standard Code for Information Interchange) option to 
the SAVE and LOAD commands. It would be similar to 
the "A" option now available with Disk BASIC'S SAVE 
command. That simple change would make a world of 
difference for Pascal programmers. 

Compiler 

Pascal-80 follows the description of Pascal given in the 
excellent tutorial by Peter Grogono, Programming in 
Pascal (Reading MA: Addison-Wesley, 1978). The com- 
piler is based on the original language as designed by 
Niklaus Wirth. However, Pascal-80 does not implement 



308 December 1981 © BYTE Publications Inc 



Circle 64 on Inquiry card. 



Computer experts 
(the pros) usually have big 
computer experience. 
That's why when they shop 
system software for Z80 
micros, they look for 
the big system features 
they're used to. And that's 
why they like Multi-User 
OASIS. You will too. 



DATA INTEGRITY: FILE & 
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The biggest challenge 
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Pros demand file & 
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OASIS has it. 



SYSTEM SECURITY: 
LOGON, PASSWORD 
& USER ACCOUNTING 



Controlling who gets on 
your system and what they 
do once they're on it is the 
essence of system security. 

Circle 344 on inquiry card. 



(THEN COMPARE.) 



Without this control, 
unauthorized users could 
access your programs and 
data and do what they like. 
A frightening prospect 
isn't it? 

And multi-users 
can multiply the problem. 

But with the Logon, 
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Level features of Multi-User 



OASIS, a system manager 
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for how long. 

Pros insist on these 
security features. 
OASIS has them. 



EFFICIENCY: 
RE-ENTRANT BASIC 



A multi-user system 
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on computers limited 
to 64K memory. 

OASIS Re-entrant 
BASIC makes it practical. 

How? 

Because all users use a 
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module, to execute their 
compiled programs, less 



memory is needed. Even 
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your pay-off is cost saving 
and more efficient use 
of all the memory you have 
available — because it 
services more users. 

Sound like a pro feature? 
It is. And OASIS has it. 



AND LOTS MORE... 



Multi-UserOASIS supports 
as many as 1 6 terminals 
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56K memory. Or, with 
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Multi-Tasking lets each 
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And there's our BASIC- 
a compiler, interpreter and 
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An OASIS exclusive. 

Still more: Editor; Hard 
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Keyed (ISAM), Direct & 
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Our documentation is 
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MAKES MICROS RUN LIKE MINIS 



BYTE December 1981 



309 



the full Pascal language. The limitations and restrictions 
are listed in table 2. On the positive side, Pascal-80 pro- 
vides a number of extensions to the original language. 
These are listed in table 3. 

The standard Pascal functions are provided: ABS, 
ARCTAN, COS, EOF, EOLN, EXP, LN, ODD, ORD, 
PRED, ROUND, SIN, SQR, SQRT, SUCC, and 
TRUNC. They are calculated with 14-digit precision. 
Functions to access the Z80 ports (like BASIC'S INP and 
OUT functions) are not provided. Also, there is no ran- 
dom-number generator. 

Although all the TRS-80 graphics characters can be 
printed through use of the CHR function, there are no 
equivalents to BASIC'S SET, RESET, and POINT func- 
tions for dealing with a single graphics pixel. There is also 
nothing like BASIC'S PRINT @ statement that positions 



Arrays of characters may be printed with a single statement 
(ie: WRITE(STRING) will write out the ARRAY of CHAR 
called STRING). 

In addition to type REAL, with 14-digit precision, Pascal-80 
adds REAL6, with 6-digit precision. REAL6 saves space 
when declaring large arrays. It doesn't save much time, 
however, since all calculations are carried out internally 
with 14-digit precision. REAL6 variables that are not mem- 
bers of an array or record may not be passed to a proce- 
dure or function as value parameters. 

The files INPUT and OUTPUT need not be included in the 
PROGRAM statement, and the program name is also op- 
tional. The file LP is predefined to be the line printer. 

The CASE statement is extended to include an ELSE clause 
that is executed if none of the cases is satisfied. If no case 
is satisfied and there is no ELSE clause, control falls 
through to the next statement with no error condition raised. 

Output formatting is provided with the syntax WRITE(ex- 
pression : fieldwidth : digits). This says to write the value of 
expression in a field of fieldwidth columns with digits 
number of digits after the decimal point. A field width of - 1 
results in scientific notation; a field width of results in the 
default format, also used if no format parameters are 
specified (eg: WRITE(express/on)). The default format is to 
print the number with a leading blank, and as many digits 
after the decimal point as necessary, up to 14 significant 
digits. 

Built-in functions and procedures: 

CHR(n) returns the character, type CHAR, whose ASCII 
value is n. 

CLS clears the screen. 

POKE(address,va/ue) places a 1-byte value from to 255 in- 
to the memory location address. 

INKEY is like the BASIC INKEY$ function; it returns a CHAR- 
type value corresponding to the key pressed. If no key is be- 
ing pressed, it returns CHR(O). 

CALL(address,va/ue) places a 1-byte value from to 255 in 
the A register and calls a Z80 subroutine at address. The 
contents of the Z80's A register after the call are returned 
as type INTEGER. 

MEM returns the number of bytes of free memory. 

PEEK(address) returns the contents of address. 

FP(expression) returns the fraction part, or mantissa, of a 
REAL number. 

EX(expression) returns the exponent of a REAL number. 
Table 3: Enhancements and special features of Pascal-80. 



the cursor on the screen. Pascal procedures can be written 
to handle all these, but they really should be built into 
any language implemented for the TRS-80. 

READ and WRITE statements are provided to perform 
sequential input and output to disk files. The statement 
SEEK(expression, filename) allows random file access by 
positioning to the record whose number is given by ex- 
pression. You can thus SEEK a particular record, and 
then READ and/or WRITE that record, performing an 
update in place on the file. This powerful extension over- 
comes an oft-voiced objection to many implementations 
of Pascal disk input /output: they do not provide random 
file access. 

I do have a few complaints and suggestions for im- 
provements to the system. 

There is a restriction on SEEK that may cause problems 
for some applications; you cannot SEEK past the 
65,535th byte of a file. In many applications, files larger 
than 64 K bytes are common. Considering the space 
available on the double-density Model III disks, and the 
general trend toward increasing disk-storage space on 
microcomputers, I believe this SEEK limit should be 
remedied in a future release of Pascal-80. 

One serious limitation of Pascal-80's disk-file interface 
is that file names are determined at compile-time. That is, 
you must specify the actual file name in your program 
when you edit it. Once compiled, that file name cannot 
be changed without reediting the program and compiling 
again. This means you cannot write a general-purpose 
program to work on any file, getting the specific file 
name from the user when the program is run. 

Use of the PEEK, POKE, and CALL functions/proce- 
dures is made difficult by two things: 

• Pascal-80's use of memory is undocumented; no mem- 
ory-map is provided. 

• No way is provided to reserve memory for user ma- 
chine-language programs or data. There is nothing equiv- 
alent to BASIC'S MEMORY SIZE? question. Instead, 
Pascal-80 uses all memory available. 

These factors make it almost impossible to integrate user- 
written machine-language routines into the Pascal-80 en- 
vironment. Regrettably, this rules out the use of nonstan- 
dard printers that require special driver routines loaded 
in high memory. 

If I may editorialize a bit, it seems it is time to stan- 
dardize the protocol to be followed when reserving 
TRS-80 high memory for user-defined machine-language 
programs. One of the smoothest things about operation 
of "second-generation" TRS-80 operating systems such as 
LDOS, NEWDOS/80, etc, is the way they handle this. 
The memory location hexadecimal 4049, referred to in 
the literature as HIGH$ and HIMEM, contains the ad- 
dress of the highest byte in memory available for use by 
any program. Memory starting at the next byte past this 
address is reserved. Any program that needs to use high 
memory should allocate it downward from the address 
pointed to by HIMEM, and then reset HIMEM to point 



310 Deotmber 1981 © BYTE Publications Inc 




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BYTE December 1981 311 



below the block of memory it just allocated for itself. 
Programs such as Pascal-80 should check HIMEM when 
they start, and not use any memory above the current 
value of HIMEM. If all programs followed this protocol, 
life would be much easier for the user — there would be no 
need to worry about conflicts in memory usage between 
different machine-language drivers, or to remember what 
the highest available memory location is in order to sup- 
ply it to a program such as BASIC every time it is run. I 
hope a future release of Pascal-80 will follow this pro- 
tocol. 

Performance 

As far as the performance of Pascal-80 programs is 
concerned, I made some very rough timings and found 
that for a short, simple looping-type program using IN- 
TEGER variables, Pascal-80 is four to five times faster 
than an equivalent BASIC program. This advantage 
should increase for larger programs because BASIC takes 
longer to find the destination of a GOTO, GOSUB, etc, 
as program size grows, and it takes longer to look up a 
variable as the number of program variables increases. 
With Pascal-80, such things are resolved at compile-time 
rather than run-time; thus, the time taken at run-time is 
independent of program size. 

Programs involving extensive floating-point computa- 
tions are potentially faster in BASIC than in Pascal-80. 
This is due to the latter's exclusive use of double-precision 
arithmetic. If all you need is single-precision arithmetic 



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for your computations, BASIC will do them faster. 

Run-time errors result in clear, English error messages 
that specify the hexadecimal offset of the p-code instruc- 
tion that caused the error. The offsets corresponding to 
the beginning of each line of Pascal-80 source code ap- 
pear in the listing created during compilation. This 
method enabled me to pinpoint easily the source of every 
run-time error encountered. A run-time error terminates 
program execution. There is no provision for program 
trapping of run-time errors, as the ON ERROR statement 
of BASIC allows. 

Documentation and Support 

Pascal-80 comes with a small booklet that adequately 
describes how to use the editor, monitor, and compiler, 
explains the limitations and extensions Pascal-80 makes 
to standard Pascal, and lists the error messages generated 
by the compiler and the run-time system. No comprehen- 
sive description of the language implemented by 
Pascal-80 is provided. Examples are few and are directed 
toward pointing out differences between Pascal-80 and 
standard Pascal, rather than toward teaching about the 
language. 

The manual does not purport to be a beginner's guide 
or even a reference manual, and you will definitely need a 
textbook such as Grogono's to use this system. I had no 
trouble figuring out the system, but I am an experienced 
programmer; this manual would be rough going for a 
novice. I have seen much worse documentation than this; 
but I have also seen much better for products costing 
much less. 

I believe the microcomputer software market has 
matured sufficiently that there is no longer any excuse for 
incomplete, difficult-to-read documentation. For a pro- 
gram costing almost $100, I expect much more than a 
14-page leaflet. It would pay for TSE-Hardside to invest 
in a professionally written manual for a major product 
like a Pascal compiler. 

Conclusions 

If my criticisms seem harsh, let me emphatically state 
that I am very excited about having a nearly complete im- 
plementation of Pascal for the TRS-80. Pascal-80 is better 
suited to the TRS-80 than any Pascal system I have seen 
so far. It is extremely fast, and it provides niceties like 64 
significant characters in variable names, 14-digit preci- 
sion on all transcendental functions, and the sheer 
elegance of Pascal's defined-type mechanism. 

From my conversations with Gates, it is apparent he 
intended to provide a teaching tool people could use to 
learn Pascal programming as an alternative to BASIC. He 
has certainly done this and more. Pascal-80 is suitable for 
many things now being done in BASIC. In fact, it is 
because Pascal-80 does so much more than just provide a 
teaching tool that I hope he will consider implementing 
the minor enhancements I have suggested. It would be 
nice to be able to use Pascal-80 for all program develop- 
ment on the TRS-80, instead of being forced to use 
BASIC for some things. ■ 



312 December 1981 © BYTE Publications Inc 



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BYTE December 1981 



313 



BYTELINES 



News and Speculation About Personal Computing 

Conducted by Sol Llbes 



Looking Back On 
1981: Looking back on the 
year, I have been struck by 
three developments. The 
first is that probably more 
new microcomputers were 
introduced in 1981 than in 
all the previous years com- 
bined. Second, that this was 
the year in which the "big- 
gies" (eg: IBM, Xerox, etc) 
finally realized they could 
no longer ignore the person- 
al-computing market and 
jumped into the fray. Third, 
in 1981 the Japanese began 
exporting personal comput- 
ers to the US. 

IBM, whose earnings for 
the first half of the year rose 
5.3% (one-third the inflation 
rate), saw minicomputer 
makers like DEC (Digital 
Equipment Corporation) in- 
crease their earnings over 
35%. Personal-computer 
makers like Apple had an in- 
crease of more than 200% . 
In the course of the last 10 
years, IBM has seen its share 
of the market decrease from 
more than 50% to less than 
25% . If this trend were to 
continue, IBM would be- 
come a minor entity in the 
computer market within five 
years. 

Thus, IBM had no choice 
but to enter the personal- 
computer marketplace. By 
hesitating on minicomput- 
ers, IBM left the field wide 
open for DEC. This has re- 
sulted in DEC garnering $3.2 
billion in minicomputer 
sales and IBM having only a 
small slice of the minicom- 
puter market. In the micro- 
computer market, Apple, for 
example, will probably show 
about $350 million sales this 
year and possibly $600 mil- 
lion next year. The question 
is: Has IBM again waited too 
long? 



No one doubts that the 
IBM Personal Computer is a 
terrific product. Although it 
offers no innovative fea- 
tures, it does have a new 
price/performance ratio 
from a company with the 
strongest marketing organ- 
ization in the world. The Per- 
sonal Computer is being sup- 
ported by $12.5 million that 
IBM will spend on television 
and print advertising. With- 
out a doubt, IBM did a con- 
siderable amount of market 
research in deciding which 
way to attack the personal- 
computing market. 

Several microcomputers 
are already on the market 
with features virtually iden- 
tical to the Personal Com- 
puter's— some even have 
more power— but none at 
the IBM price or with its ser- 
vice support. It is rumored 
that more than 40,000 Per- 
sonal Computers were or- 
dered on the day it was un- 
veiled. Now, the questions 
are: 

• How much business will 
IBM snatch away from Ap- 
ple, Tandy, Commodore, 
and Atari? 

• How will Apple and the 
others respond? 

• How will the Japanese 
compete with IBM? 

IBM's Personal Computer 
marks a distinct shift in the 
company's traditional way 
of doing business, which was 
"we make it and sell it our- 
selves." Actually this policy 
change started to take effect 
some time ago, but IBM tries 
not to talk about it. Early 
last year, for example, it in- 
troduced a video-display ter- 
minal that could be used 
with non-IBM equipment— a 
first— and discovered that 



sales for this unit were so 
great that delivery now re- 
quires 4 to 6 months' lead 
time. Only two weeks before 
the Personal Computer was 
released, IBM quietly an- 
nounced the System/23, 
which uses the 8086 micro- 
processor (big brother to the 
8088 used in the Personal 
Computer). The System/23 
really begins where the Per- 
sonal Computer ends, with 
full-size floppy disks, multi- 
users, etc. In effect, it pro- 
vides upward compatibility 
for users starting out with 
the IBM Personal Computer 
who find its small disk-stor- 
age space and limited I/O 
(input/output) options 
restricting. 

Another startling change 
in IBM policy is its selling 
the system through comput- 
er stores (currently there are 
contracts with Computer- 
Land and Sears Roebuck). 
IBM has also announced dis- 
counts for educational users 
and other quantity buyers. 
IBM's most surprising policy 
shift is in encouraging soft- 
ware development by out- 
siders. IBM intends to mar- 
ket the software and pay 
royalties to the authors. 
Probably nine out of ten of 
the 40,000 computers 
ordered on Day-One were 
from software developers. 
(What a way to sell comput- 
ers!) After all, the profits for 
IBM are really in hardware 
sales and not in software. 
Osborne is proving this by 
practically giving away soft- 
ware with its computer. 
Also, it is impossible for a 
manufacturer to protect it- 
self against software com- 
petition. IBM learned this 
when Digital Research in- 
troduced a version of CP/M 
for the Displaywriter (which 



also uses an 8086 micropro- 
cessor). 

The last question is how 
will the microcomputer 
makers in the US and Japan 
respond to the IBM entry? 
Rumors are circulating that 
Apple is about to introduce 
two new computers: its long- 
awaited 16-bit system, using 
the Motorola 68000, packed 
with 128 K bytes of pro- 
grammable memory, and 
available in both desktop 
and suitcase versions, and a 
low-cost version of the Ap- 
ple II using 16 K-bit memory 
chips that later can be re- 
placed by 64 K-bit chips 
when these are available 
in quantity. The Japanese 
are thought to be developing 
8088- and 8086-based per- 
sonal computers that will be 
"plug-compatible" with 
CP/M software developed 
for the IBM Personal Com- 
puter. Several Japanese 
companies have signed 
licenses for CP/M-86 and 
have been negotiating with 
Peachtree Software (supplier 
of the IBM accounting pack- 
age), SofTech Microsystems 
(supplier of the IBM Pascal 
package), Microsoft (sup- 
plier of IBM BASIC), and Per- 
sonal Software (supplier of 
IBM VisiCalc). It is apparent 
that in 1982 personal-com- 
puter buyers will be able to 
choose among many dif- 
ferent computers that run 
the same operating systems 
and applications software. 



B^lsk-Drlve Happen- 
ings: Seagate Technol- 
ogy—a Shugart Associates 
spin-off and the first com- 
pany to ship quantities of 
5 1 4-inch Winchester hard 
disks— has announced that 
sales totaled almost $10 



314 December 1981 © BYTE Publications Inc 



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million, with nearly $2 mil- 
lion in profits, in its first year 
of operation. Meanwhile, 
Shugart Associates is 
rumored to be redesigning 
its popular SA200 5-inch 
floppy-disk drive. It will be 
called the SA210, will be 
made in Japan by Matsu- 
shita, and will sell for less 
than $90 in quantity. 

In other action, Amlyn 
Corporation, San jose, Cali- 
fornia, has introduced a 
5-inch floppy-disk drive with 
a selector mechanism that 
selects any of five 5-inch 
floppy disks (under comput- 
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National Computer Confer- 
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640-megabyte, Winchester 
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largest yet. 



I rue Three-Dlmen- 
slonal Computer-Display 
Debuts: Cenisco Computer 
Corporation, Costa Mesa, 
California, is now shipping 
video systems that display 
true three-dimensional im- 
ages. The computer presents 
pictures of successively 
deeper layers of space-filling 
image via a moving mirror. 
This is done rapidly enough 
to create a single flicker-free 
image. Priced at $100,000 
each, the units are expected 
to be useful in seismic-data 
analysis, oil exploration, 
computer-aided design, 
medical imaging, and earth- 
quake prediction. 

Imandom Rumors: This 
spring Fujitsu Ltd, now a sec- 
ond source for the 8086 and 
8088 microprocessors, is ex- 
pected to announce a word 



processor and personal com- 
puter using these chips. . . . 
Tandy is said to be working 
on a system based on the 
68000 to be released any 
day. It's also stepping up 
software production and is 
attempting to release be- 
tween four and 12 new soft- 
ware packages a month. 
Following in the footsteps of 
IBM, it is actively soliciting 
software from outside devel- 
opers. Tandy's biggest soft- 
ware push is in producing 
business software for the 
Models II and III. Tandy 
may offer CP/M for these 
machines. A VisiCalc-like 
product is also rumored for 
the low-cost Color Comput- 
er. .. . Xerox is reported to be 
working on a Z80-based 
computer that is less expen- 
sive than its current Model 
820. It has been dubbed the 
Inchworm (the code name 
for the 820 was the Worm, 
for Wonderful Office Re- 
source Machine). It is ex- 
pected to sell for under 
$1000, have 16 K bytes of 
programmable memory, 
64 K bytes of read-only 
memory, an 80 by 25 dis- 
play, RS-232C printer and 
modem ports, and CP/M- 
compatibility. . . . Wang is 
putting the final touches on 
its CP/M-compatible person- 
al computer. . . . DEC is 
rumored to be prepared to 
announce its TC personal 
computer, built around an 
LSI-11. ... A major Japanese 
company has invested over 
$100 million in CMOS 
research. Look for resulting 
major advances in memory 
technology in a year of so. 
. . . Also from Japan comes 
word of a new computer ter- 
minal with many of the 
features of the Xerox Star, 
but at a substantially reduc- 
ed price. . . . Meanwhile, an- 
ticipate IBM jumping onto 
the UNIX bandwagon, with 
versions for the Series 1 and 
4300 computers. The soft- 
ware is being developed by 
an independent software 



house. . . . Vadic may be 
close to introducing a 
4800 bps modem for voice- 
grade telephone lines. The 
price range will probably be 
in the $2-3000 neighbor- 
hood. Rockwell Interna- 
tional and Racal Corpora- 
tion are also said to be work- 
ing on 4800 and 9600 bps 
modems for voice-grade 
lines. . . . Hitachi is expected 
to start shipping large- 
volume quantities of the 
68000 microprocessor at 
substantially reduced prices. 
. . . Rumors persist that 
Motorola has 13 MHz ver- 
sions of the 68000 running in 
its lab and that Intel has 
14 MHz versions of its 8086 
running. . . . 



IM. 



lew Loglc-Clrcult Re- 
search: IBM is researching 
new types of logic circuits 
that could have far-reaching 
effects on the size, cost, and 
performance of future com- 
puters. Among the new cir- 
cuits is a device called "low- 
voltage inverter" (LVI) logic. 
It is twice as fast as emitter- 
coupled logic (ECL), which is 
the fastest logic type in cur- 
rent use, and has the same 
size and power consumption 
as TTL (transistor-transistor 
logic), which is used in most 
mini- and microcomputers. 
With propagation delays of 
300 picoseconds, LVI prom- 
ises to be a new price/perfor- 
mance breakthrough. 

Cornell University's 
Microfabrication Laboratory 
in Ithaca, New York, and the 
Naval Research Laboratory 
in San Diego have both dis- 
closed that they are re- 
searching the use of elec- 
troactive polymers for mole- 
cular electronic-switching 
devices. Enzymes would be 
used to perform logic opera- 
tions. Due to the fact that 
enzymes are organic mole- 
cules, genetic engineering 
and recombinant-DNA tech- 
nology would be used to 
subassemble these organic 



molecules. The result would 
be the miniaturization of 
logic circuitry by two orders 
of magnitude beyond the 
current limits of optical 
lithography and beyond any- 
thing achievable with elec- 
tron-beam or X-ray litho- 
graphy. Although still in very 
early stages, this technology 
holds promise for use in fu- 
ture computers. 



Js-50 Status Report: Al- 
though smaller than the 
S-100-bus-based microcom- 
puter market, the SS-50's 
market is flourishing. The 
SS-50 bus was introduced in 
late 1975 for 6800-based sys- 
tems. Today, the most popu- 
lar microprocessor used on 
the SS-50 bus is the powerful 
6809, although other proces- 
sor cards, such as the Z80, 
are also available. 

Four hardware vendors 
dominate the SS-50 market- 
place: Southwest Technical 
Products Corporation 
(SwTPC), San Antonio, Texas 
(the creator of the bus); 
Gimix, Chicago, Illinois; Per- 
com Data, Garland, Texas; 
and Smoke Signal Broad- 
casting, Westlake Village, 
California. By contrast, the 
S-100 market is shared by 
more than 70 suppliers. It is 
known that several SS-50 
makers are working on im- 
plementing the 68000 for the 
SS-50 bus structure. 

Three operating systems 
reign over the SS-50 market: 
FLEX, a single-user operating 
system, and UniFLEX, a multi- 
user system, both from Tech- 
nical System Consultants, 
West Lafayette, Indiana; and 
OS-9 from Microware, Des 
Moines, Iowa. FLEX operates 
on the 6800, while UniFLEX 
and OS-9 operate on the 
6809. UniFLEX and OS-9 pro- 
vide some UNIX-like fea- 
tures and support multiple 
users. Two magazines also 
cater to SS-50 users. 

Even though the 6800 and 
6809 processors are avail- 



316 December 1981 © BYTE Publications Inc 



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©1981 Microcomputer Applications 



MICROSTAT™ Release 2.0 

a c [x " Just some of the new features of Microstat Rel. 2.0 in- 
clude: new programs for moments about the mean, skewness, 
kurtosis and stepwise multiple regression, longer file names, faster 
sort routine, the ability to declare each data file's numeric precision 
and drive location plus an expanded user's manual with new appendi- 
ces for the equations and file structures used in Microstat. Also 
included is a Data Management Subsystem for file maintenance (edit, 
list, destroy, augment, sort, rank-order, move and merge) plus trans- 
formations (add, subtract, multiply, divide, reciprocal, log, natural log 
and antilog, exponentiation and linear) that allow you to create new 
variables from existing variables. 

After file creation with DMS, programs for analysis include: Descrip- 
tive statistics, Hypothesis testing (mean and proportion), ANOVA 
(one-way, two-way, and random blocks), Scatterplots, Frequency 
distributions. Correlation analysis. Simple, Multiple and Stepwise 
Multiple Regression (including files larger than available memory), 
Time series, 11 Nonparametric tests, 8 Probability distributions, 
Crosstabs and Chi-square, Combinations, Permutations and Factor- 
ials (up to one million factorial). All program output is neatly fnrmatted 
for easy use. 

The price for Microstat Rel. 2.0 is $295.00 and the user's manual is 
available for $25.00 (credited towards purchase) and includes sample 
printouts with file lables that reference standard statistical texts and 
journals so you can compare the results from Microstat to those 
produced on much larger systems. Compare Microstat to any other 
package on the market and we think you'll agree that Microstat is the 
best at any price. 



I Interchange) 

l(nterchange) is a general purpose file maintenance program for use 
with the CP/M™ operating system. Since it is a single program 
written in optimized Z-80™ code, it is much faster and easier to use 
than other file maintenance programs. Features include: DIR as usual 
plus listing all files excluding those with a specified character(s), ERA 
as usual plus exclusive erases. Also, a "Q" switch can be used to query 
each erase, a "W" allows erases of R/'O files without query (normally 
you are queried), and an "R" switch if system files are to be included, 
LIST permits listings and uses TAB, WIDTH, LINES and WRAP for 
control, COPY as usual plus exclusive copies and supports the "Q", 
"W" and "R" switches plus an "E" switch for query on existing fil